Article

Reintroduction success of threatened Australian trout cod (Maccullochella macquariensis) based on growth and reproduction

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Abstract

Internationally, re-introductions of endangered species into their former ranges have largely failed. Here we assess a successful reintroduction program of the endangered trout cod (Maccullochella macquariensis) and examine factors contributing to this success. Stocking of marked fish (all stocked fish were marked) occurred between 1997 and 2006 in the Ovens River, south-eastern Australia, where trout cod were historically abundant but locally extinct by the 1980s. We found no natural recruits (i.e. from spawnings of stocked fish in the wild) over the age of six, indicating that natural recruitment started at most five years after stocking began. Of the 83 fish we examined for sexual maturity, 12 were immature, 20 were male, and 51 were female. The body length at which 50% of the population can be considered mature was 325 and 250 mm for females and males, respectively. The length at which 90% of the population was mature was 394 and 318 mm for females and males, respectively. The smallest mature female was 245 mm. Average relative fertility was 9 eggs g–1 fish weight. The results we obtained provide valuable insights into the aspects contributing to the success of reintroduction programs for endangered freshwater species.

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... However, there is substantial variation in the success of stocking programs around the world (Buynak and Mitchell 1999;. Although there has been particular success from stocking when the focus is to augment recreational fishing opportunities or where the population is already greatly reduced and natural recruitment is low (Lorenzen 2005;Hunt et al. 2010;Lyon et al. 2012), there have also been many examples of stocking resulting in poor or unintended outcomes (Araki and Schmid 2010). Poor stocking outcomes have been attributed to limited survival of stocked individuals (Fjellheim et al. 1995), reduced fitness resulting from unintentional selection of negative behavioural and physiological traits within the hatchery (Hutchings 2014) and mismatches between individuals and the stocking location environment (Stringwell et al. 2014). ...
... For example, successful stocking of golden perch has occurred in the absence of a natural recruiting population already existing , whereas limited benefits have been observed when stocking occurs in the presence of existing recruiting populations (Thiem et al. 2017). In addition, the successful rehabilitation of a trout cod Maccullochella macquariensis population was largely dependent on two successful stocking years, when environmental conditions were optimal (Lyon et al. 2012). ...
... Many hatchery protocols already exist to enhance the production and survival of fish before release, therefore ensuring high costeffectiveness at the production stage (Bettinger and Bettoli 2002;Forbes et al. 2016). There are also other existing strategies to ensure the success of stocked fish, such as ensuring that fish encounter favourable environmental conditions when they are stocked, by timing flow releases from impoundments, inducing higher river productivity and promoting local survival (Bearlin et al. 2002;Lyon et al. 2012). The results of the present study indicate that phenotypic traits can affect the future of stocked fish in the wild, but we suggest that the management of individuals within the hatchery is also important. ...
Article
Stock enhancement is an important tool used to rebuild depleted fish populations or enhance recreational fishing. Hatchery-reared individuals can express trait differences, such as growth, which may affect later survival. However, there is little understanding of how early life growth variation affects stocking success. We examined early life growth of golden perch Macquaria ambigua and assessed how growth within hatcheries affects the survival of stocked fish. We measured daily otolith increment widths at 10, 20 and 30 days after hatching, but before stocking into lakes in south-eastern Australia. Mean growth decreased with age, but variation in growth increased. We then compared the early life growth of these individuals to those recaptured after 2 years at liberty (age-2+). Faster individual growth between 20 and 30 days was positively correlated with increased length at stocking. Mean growth between 20 and 30 days of age-2+ fish was higher than that of young-of-year fish, but among-individual variation in growth did not differ between the two groups. These results suggest that individuals with fast hatchery growth have increased survival to 2 years. We propose that enhancing growth within hatcheries may increase the survival of stocked fish, and thus the cost-effectiveness of fish stocking.
... This means 24 years have elapsed since the first stocking, but only 8?10 years since the majority of the stocking occurred. Trout Cod become sexually mature after 3?5 years (Lintermans, 2007), producing noticeably more recruits after 6 years of age (Lyon, Todd & Nicol, 2012). This means that there has been opportunity for at least 4 generations to occur by 2011?the beginning of this study. ...
... At least one study has found deviation from the expected sex ratio where females dominated by 2.5 to 1. The same authors report previous unpublished findings of highly skewed sex ratios of up to nine males to each female (Lyon, Todd & Nicol, 2012). Identification of sex-linked markers would be helpful for future studies of this and other species. ...
... Given restocking commenced in 1988 and increased after 1992, introgression in even deeper backcrosses is possible but more sampling and species specific sensitive analytical techniques might be used to identify evidence of this. The national Trout Cod restocking program has been through a number of iterations and changes in approach, with stocking moving from releases of small numbers of fish (<1,000) for one or two years to releases of tens of thousands of fish for 5?10 years (Lyon, Todd & Nicol, 2012; Koehn et al., 2013). The upper Murrumbidgee stocking program sits midway in this stocking approach and likely still suffered from insufficient fish being stocked over a concentrated temporal and spatial scale. ...
Article
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Rates of hybridization and introgression are increasing dramatically worldwide because of translocations, restocking of organisms and habitat modifications; thus, determining whether hybridization is occuring after reintroducing extirpated congeneric species is commensurately important for conservation. Restocking programs are sometimes criticized because of the genetic consequences of hatchery-bred fish breeding with wild populations. These concerns are important to conservation restocking programs, including those from the Australian freshwater fish family, Percichthyidae. Two of the better known Australian Percichthyidae are the Murray Cod, Maccullochella peelii and Trout Cod, Maccullochella macquariensis which were formerly widespread over the Murray Darling Basin. In much of the Murrumbidgee River, Trout Cod and Murray Cod were sympatric until the late 1970s when Trout Cod were extirpated. Here we use genetic single nucleotide polymorphism (SNP) data together with mitochondrial sequences to examine hybridization and introgression between Murray Cod and Trout Cod in the upper Murrumbidgee River and consider implications for restocking programs. We have confirmed restocked riverine Trout Cod reproducing, but only as inter-specific matings, in the wild. We detected hybrid Trout Cod–Murray Cod in the Upper Murrumbidgee, recording the first hybrid larvae in the wild. Although hybrid larvae, juveniles and adults have been recorded in hatcheries and impoundments, and hybrid adults have been recorded in rivers previously, this is the first time fertile F1 have been recorded in a wild riverine population. The F1 backcrosses with Murray cod have also been found to be fertile. All backcrosses noted were with pure Murray Cod. Such introgression has not been recorded previously in these two species, and the imbalance in hybridization direction may have important implications for restocking programs.
... These subsequent stocking regimes for trout cod have been more successful, with natural recruitment observed or inferred in at least six of the areas. What might be described as 'self- sustaining' populations now occur in the mid-Murrumbidgee (Gilligan 2005;Ingram and Thurstan 2008), the lower Ovens River ( Lyon et al. 2012) and mid-Goulburn Rivers ( Koster et al. 2004; Table 3). Monitoring frequency and effort, however, have been variable and the time between initiating stocking and observing recruitment has been 5-13 years ( Lyon et al. 2012; M. Lintermans, pers. ...
... What might be described as 'self- sustaining' populations now occur in the mid-Murrumbidgee (Gilligan 2005;Ingram and Thurstan 2008), the lower Ovens River ( Lyon et al. 2012) and mid-Goulburn Rivers ( Koster et al. 2004; Table 3). Monitoring frequency and effort, however, have been variable and the time between initiating stocking and observing recruitment has been 5-13 years ( Lyon et al. 2012; M. Lintermans, pers. comm.). ...
... found the Murray River population (11 haplotypes) to be sig- nificantly different from both the translocated Seven Creeks population (2 haplotypes) and the stocked population in the Ovens and King Rivers (6 haplotypes). A recent microsatellite- marker study showed that although there were more alleles detected in the stocked population of the Ovens River (total 55) than in the Murray River population (total 49), these populations were genetically homogeneous ( Lyon et al. 2012). This outcome is likely to be the result of successful application of breeding- program protocols, which were established early in the stocking program and aimed to maximise the genetic diversity of the fish produced. ...
Conference Paper
Recovery of threatened species is often necessarily a long-term process but one which is rarely successful or well documented. This paper details the progress towards the recovery of an iconic, long-lived Austtralain freshwater fish species: the trout cod Maccullochella macquariensis, first listed as threatened in the 1980s. The objectives, actions and progress of three successive national recovery plans (spanning 18 years) are assessed, documenting changes to population distribution and abundance and updating ecological knowledge. Increased knowledge (especially breeding biology and hatchery techniques, movements, habitats and genetics) has greatly influenced recovery actions and the use of a population model was developed to assist with management options and stocking regimes. Key recovery actions include: the stocking of hatchery-produced fish to establish new populations; regulations on angling (including closures); education (particularly identification from the closely related Murray cod M. peelii); and habitat rehabilitation (especially re-instatement of structural woody habitats). In particular, the establishment of new populations using hatchery stocking has been a successful action. The importance of a coordinated long-term approach is emphasised and whilst there is uncertainty in ongoing resourcing of the recovery program, much has been achieved and there is cautious optimism for the future of this species.
... Attempts to recover depleted populations have been implemented worldwide [3] as species loss can affect the stability, resilience, and food web dynamics of aquatic ecosystems and also impact the welfare of human populations that depend on fisheries resources [4][5][6]. The reintroduction of captive-bred fishes in areas where wild populations have been extinguished has been commonly used as a fisheries management tool and for conservation purposes [7,8]. ...
... Several studies have demonstrated the importance of post-release survival, dispersal, and growth to reproductive age [8,9,[19][20][21] for the success of reintroduction programs and that postrelease mortality has a large impact over the initial population size [22]. It is considered for larger juveniles to have higher chances of surviving when released into the wild [23,24], and thus, the release of yearling juveniles was considered appropriate for the purpose of this experiment. ...
... Studies of population modeling for the reintroduction of endangered fishes suggest that long-term (5-10 years) stocking strategies are more likely to succeed by increasing the chances of the stocked cohort encountering favorable environmental conditions [8,27,28] Addressing the cause of a population's initial decline is also crucial for the reestablishment of locally extinct populations and the long-term success of a reintroduction program [3]. In the Upper Uruguay River, physical barriers to migration, deforestation, and overfishing led to the decline of the species [12,13]. ...
Article
Full-text available
The reintroduction of threatened fish species in areas where wild populations have been depleted due to anthropogenic impacts is an increasingly popular conservation tool and mitigation policy. Despite the importance of fish reintroduction for conservation purposes, little is known about its efficiency. Here, we assessed the viability of reintroduction of the endangered migratory fish, Brycon orbignyanus, in an area of the Upper Uruguay River basin where the species has not been reported for more than 30 years. We released 4000 yearling juveniles in the Pelotas River in 2014 and maintained 400 juveniles in captivity as a control population. After three years, a total of 13 individuals was recaptured, of which, 10 were considered sexually mature with first maturation being recorded in animals larger than 42 cm in total body length. The age–length comparison with a control population growth curve showed that recaptured fish were slightly bigger than those in captivity. Furthermore, important ecological attributes as schooling behavior and dispersal capacity were recorded for all recaptured individuals. Combined, our results suggest that the re-establishment of a self-sustained population of locally extinct species B. orbignyanus in the Pelotas River may be successful if sustained over time and supported by conservation policies.
... Conservation stocking and translocation programs (mainly 0þ fish) have recently resulted in populations being re-established in the mid-and upper Murrumbidgee (including tributaries), upper Murray, lower Goulburn and lower Ovens rivers , Seven Creeks (Goulburn catchment, Vic.), Cataract Dam (Nepean catchment, NSW; Douglas et al. 1994;Lintermans et al. 2015) and Lake Sambell (Ovens catchment, Vic.). The successful re-establishment of the Ovens River population Lyon et al. 2012) has led to expansion into the Murray River upstream of Lake Mulwala. Stocking of ongrown hatchery-reared fish (age 2þ) has had limited success Ebner and Thiem 2009). ...
... Changes to the natural hydrologic regime can disrupt cues that initiate maturation and spawning, in addition to altering the conditions suitable for recruitment, and may have had more of an effect on post-spawning recruitment than on the prevention of spawning (Humphries and Lake 2000) Loss of hydraulic complexity due to weir pools in the lower Murray River ( Before spawning Sexual maturity At 3-5 years, with M generally younger and smaller than F (M .350 mm (570 g) and F .430 mm (1200 g); see Gooley in Koehn and O'Connor 1990;Lyon et al. 2012). Smallest mature F was .245 ...
... mm (Cadwallader 1977), but the smallest confirmed to have spawned in the wild was 283 mm, 299 g and 5 years old ). In the Ovens River, 50% of the population was mature at 325 mm (F) and 250 mm (M), with 90% of the population mature at 394 mm (F) and 318 mm (M; Lyon et al. 2012). In a hatchery, the smallest F that produced viable eggs (eggs that hatched) was 360 mm (580 g), and the smallest running ripe M was 310 mm (390 g; B. Ingram, VFA, unpubl. ...
Article
Full-text available
Many freshwater fishes are imperilled globally, and there is a need for easily accessible, contemporary ecological knowledge to guide management. This compendium contains knowledge collated from over 600 publications and 27 expert workshops to support the restoration of 9 priority native freshwater fish species, representative of the range of life-history strategies and values in southeastern Australia's Murray-Darling Basin. To help prioritise future research investment and restoration actions, ecological knowledge and threats were assessed for each species and life stage. There is considerable new knowledge (80% of publications used were from the past 20 years), but this varied among species and life stages, with most known about adults, then egg, juvenile and larval stages (in that order). The biggest knowledge gaps concerned early life stage requirements, survival, recruitment, growth rates, condition and movements. Key threats include reduced longitudinal and lateral connectivity, altered flows, loss of refugia, reductions in both flowing (lotic) and slackwater riverine habitats, degradation of wetland habitats, alien species interactions and loss of aquatic vegetation. Examples and case studies illustrating the application of this knowledge to underpin effective restoration management are provided. This extensive ecological evidence base for multiple species is presented in a tabular format to assist a range of readers.
... The Murray River population appears to be more abundant than originally thought with evidence of expansion. Wild recruitment has been detected in a number of catchments (Goulburn, Ovens, Mid and Upper Murrumbidgee, Cotter) between the late 1990s and mid 2000s (Lyon et al., 2012;Koehn et al., 2013). Comprehensive monitoring of the lower Ovens River demonstrated the benefits of a long-term stocking program, with wide variation in the contribution of individual stocking events to the resultant population (Lyon et al., 2012). ...
... Wild recruitment has been detected in a number of catchments (Goulburn, Ovens, Mid and Upper Murrumbidgee, Cotter) between the late 1990s and mid 2000s (Lyon et al., 2012;Koehn et al., 2013). Comprehensive monitoring of the lower Ovens River demonstrated the benefits of a long-term stocking program, with wide variation in the contribution of individual stocking events to the resultant population (Lyon et al., 2012). Genetic analysis of upper Murrumbidgee cod larvae from 2011 -2013 found hybridization between Trout cod and Murray cod, (Couch et al., 2016) demonstrating the problem of re- establishing a threatened species into the range of an established congeneric. ...
... Goals for stock rebuilding programs include whether fish survive to reproductive size, contribute to the population genetic diversity and natural reproduction, and ultimately recreate a self-sustaining wild population (Brown and Day 2002). These have been assessed for trout cod (Ingram and Thurstan, 2008;Lyon et al., 2012) and eastern freshwater cod Maccullochella ikei (Butler, 2009;Nock et al., 2011) stock rebuilding programs. ...
... Stocking efforts for trout cod are the most substantial, both temporally spatially and in terms of numbers , however captive breeding and stocking programs also exist for small bodied threatened species including Murray hardyhead, Craterocephalus fluviatilis (Ellis et al., 2013), purple-spotted gudgeon, Mogurnda adspera, and Yarra pygmy perch, Nannoperca obscura (Saddlier et al., 2013;Hammer et al., 2013). Lyon et al. (2012) stated that stock rebuilding programs need to continue if threatened populations are to be brought back from the brink of extinction, because river restoration is unlikely to provide enough impetus for fish to recolonize previous habitats on their own. There are also calls for the hatchery breeding and stocking of other species such as the red-finned blue-eye, Scaturiginichthys vermeilipinnis (Kerezsy and Fensham, 2013). ...
Article
Full-text available
Fish stocking is commonly used in developed countries and aims to improve recreational fish stocks and rebuild threatened species populations. Fish stocking is often contentious due to its high investment, limited scientific evaluation, and typically divided opinion from key stakeholders. Debates over the efficacy and effects of fish stocking continue to occur in the absence of key information about current and past practices, and their degree of alignment with the accepted responsible approach previously published in platform papers. Consequently, using Australia as a case study, this paper presents a framework for assessing fish stocking practices. First, recent fish stocking practices were benchmarked by compiling freshwater fish stocking statistics from every state and territory in Australia. Over 84 million fish were found to have been stocked in Australia between 2009 and 2015, with recreational species, both native and salmonid, comprising the majority of numbers and weight of fish stocked, respectively. Second, historical trends in fish stocking were assessed over a 106 year period across one major jurisdiction, finding significant changes in practices including a strong move toward native species, and a reduction in the number of salmonids stocked, but an increase in size. Third, a literature review was conducted to evaluate Australia's fish stocking practices and found they could be generally considered responsible, however improvements could be made in areas highlighted. This study provides a valuable framework to assess fish stocking practices, aiding our understanding, informing future discussion, and fostering better outcomes from this popular fisheries management tool.
... The Murray River population appears to be more abundant than originally thought with evidence of expansion. Wild recruitment has been detected in a number of catchments (Goulburn, Ovens, Mid and Upper Murrumbidgee, Cotter) between the late 1990s and mid 2000s (Lyon et al., 2012;Koehn et al., 2013). Comprehensive monitoring of the lower Ovens River demonstrated the benefits of a long-term stocking program, with wide variation in the contribution of individual stocking events to the resultant population (Lyon et al., 2012). ...
... Wild recruitment has been detected in a number of catchments (Goulburn, Ovens, Mid and Upper Murrumbidgee, Cotter) between the late 1990s and mid 2000s (Lyon et al., 2012;Koehn et al., 2013). Comprehensive monitoring of the lower Ovens River demonstrated the benefits of a long-term stocking program, with wide variation in the contribution of individual stocking events to the resultant population (Lyon et al., 2012). Genetic analysis of upper Murrumbidgee cod larvae from 2011 -2013 found hybridization between Trout cod and Murray cod, (Couch et al., 2016) demonstrating the problem of re- establishing a threatened species into the range of an established congeneric. ...
Book
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DOI: https://doi.org/10.2305/IUCN.CH.2018.08.en Authors P. S. Soorae and ect .... Publication date 2018 Pages 286 Publisher IUCN/SSC Reintroduction Specialist Group, Gland, Switzerland and Environment Agency, Abu Dhabi, UAE Description This is the sixth issue in the Global Reintroduction Perspectives series and has been produced in the same standardized format as the previous five to maintain the style and quality.
... Hatchery work suggests that environmental conditions may influence sex determination at an early stage of development in some percichthyids . Lyon et al. (2012) reported 2.5 times as many females as males in a population of trout cod stocked from hatcherybred fish. Because sex-ratio biases in stocked fish have implications for recovery of populations through stocking, being able to determine the genetic sex of fish, and the extent to which it can be overridden by environmental variation, would benefit conservation management of threatened percichthyid species. ...
... Thus, environmental factors stimulating production of steroid hormones could influence genetic sex (Nakamura, 2010). Hatchery data for some percichthyids suggest the possibility of temperature-and/or hormone-driven sexratio biases Lyon et al., 2012). Our data present one possible case of sex-reversal in Macquarie perch: a homozygous YY genotype at the XY-gametologous region in one male (male 2 on Figure 1) suggests the existence of XY females, also supported by phenotypic females with Y-alleles and putatively lower fertilization rates. ...
Article
Sex‐specific ecology has management implications, but rapid sex‐chromosome turnover in fishes hinders sex‐marker development for monomorphic species. We used annotated genomes and reduced‐representation sequencing data for two Australian percichthyids, Macquarie perch Macquaria australasica and golden perch M. ambigua, and whole genome resequencing for 50 Macquarie perch of each sex, to identify sex‐linked loci and develop an affordable sexing assay. In‐silico pool‐seq tests of 1,492,004 Macquarie perch SNPs revealed that a 275‐Kb scaffold was enriched for gametologous loci. Within this scaffold, 22 loci were sex‐linked in a predominantly XY system, with females being homozygous for the X‐linked allele at all 22, and males having the Y‐linked allele at >7. Seven XY‐gametologous loci (all males, but no females, are heterozygous or homozygous for the male‐specific allele) were within a 146‐bp region. A PCR‐RFLP sexing assay targeting one Y‐linked SNP, tested in 66 known‐sex Macquarie perch and two of each sex of three confamilial species, plus amplicon sequencing of 400 bp encompassing the 146‐bp region, revealed that the few sex‐linked positions differ between species and between Macquarie perch populations. This indicates sex‐chromosome lability in Percichthyidae, supported by non‐homologous scaffolds containing sex‐linked loci for Macquarie‐ and golden perches. The present resources facilitate genomic research in Percichthyidae, including formulation of hypotheses about candidate genes of interest such as transcription factor SOX1b that occurs in the 275‐Kb scaffold ~38 Kb downstream of the 146‐bp region containing seven XY‐gametologous loci. Sex‐linked markers will be useful for determining genetic sex in some populations and studying sex chromosome turnover.
... The Murray River population appears to be more abundant than originally thought with evidence of expansion. Wild recruitment has been detected in a number of catchments (Goulburn, Ovens, Mid and Upper Murrumbidgee, Cotter) between the late 1990s and mid 2000s (Lyon et al., 2012;Koehn et al., 2013). Comprehensive monitoring of the lower Ovens River demonstrated the benefits of a long-term stocking program, with wide variation in the contribution of individual stocking events to the resultant population (Lyon et al., 2012). ...
... Wild recruitment has been detected in a number of catchments (Goulburn, Ovens, Mid and Upper Murrumbidgee, Cotter) between the late 1990s and mid 2000s (Lyon et al., 2012;Koehn et al., 2013). Comprehensive monitoring of the lower Ovens River demonstrated the benefits of a long-term stocking program, with wide variation in the contribution of individual stocking events to the resultant population (Lyon et al., 2012). Genetic analysis of upper Murrumbidgee cod larvae from 2011 -2013 found hybridization between Trout cod and Murray cod, (Couch et al., 2016) demonstrating the problem of re- establishing a threatened species into the range of an established congeneric. ...
... The Murray River population appears to be more abundant than originally thought with evidence of expansion. Wild recruitment has been detected in a number of catchments (Goulburn, Ovens, Mid and Upper Murrumbidgee, Cotter) between the late 1990s and mid 2000s (Lyon et al., 2012;Koehn et al., 2013). Comprehensive monitoring of the lower Ovens River demonstrated the benefits of a long-term stocking program, with wide variation in the contribution of individual stocking events to the resultant population (Lyon et al., 2012). ...
... Wild recruitment has been detected in a number of catchments (Goulburn, Ovens, Mid and Upper Murrumbidgee, Cotter) between the late 1990s and mid 2000s (Lyon et al., 2012;Koehn et al., 2013). Comprehensive monitoring of the lower Ovens River demonstrated the benefits of a long-term stocking program, with wide variation in the contribution of individual stocking events to the resultant population (Lyon et al., 2012). Genetic analysis of upper Murrumbidgee cod larvae from 2011 -2013 found hybridization between Trout cod and Murray cod, (Couch et al., 2016) demonstrating the problem of re- establishing a threatened species into the range of an established congeneric. ...
... Re-establishing populations of slow-maturing and long-lived species is necessarily a long-term endeavour (Koehn et al., 2013), and the recovery of endangered species with historically large geographic ranges and species that face a multitude of threats that are difficult to identify and ameliorate has proved challenging (Abbitt & Scott, 2001 (Koehn et al., 2013;Lyon et al., 2012). Yet, researchers in this system cited the increased knowledge of reproductive biology, habitat use, and genetics as largely contributing to the significant progress towards recovery (Koehn et al., 2013). ...
... One of the main factors limiting the success of freshwater fish reintroductions as a conservation strategy is the inability of managers to identify and remove impediments to the persistence of stocked fish (Cochran-Biederman et al., 2015). As long-term stocking programmes, such as those used by the SJRIP, are likely to assume that there will be ample opportunity for stocked cohorts to encounter favourable environmental conditions, and demonstrate relatively high survival rates (Lyon et al., 2012), other potential management strategies for aiding the survival of stocked fish have rarely been considered or implemented. ...
Article
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• Disruption of ecosystems by human activities has caused worldwide extinction threats, which has prompted conservationists to implement captive breeding programmes that aid the recovery of imperilled species. Understanding factors that limit the survival of hatchery‐spawned fishes after stocking is critical to future conservation efforts using captive populations. • As the size at which juvenile piscivorous fishes shift to consuming other fish can influence their survival, the transition to piscivory by hatchery‐spawned Ptychocheilus lucius Girard, 1856 (Colorado pikeminnow) was investigated after stocking the San Juan River in New Mexico, Colorado, and Utah, USA. The stable isotope ¹⁵N was used to track ontogenetic changes in the trophic position of individuals stocked at age 0, with the expectation that they would become fully piscivorous by age 2. By sampling the isotopic signatures of Colorado pikeminnow across multiple years, the ability of river discharge and densities of fish prey to explain interannual variation in trophic position was also explored. • Annual variation in river flow and the densities of fish prey had little predictive power in explaining variation in δ¹⁵N of age‐1 or age‐2 Colorado pikeminnow. After assessing the isotopic signatures of potential prey, a Bayesian isotopic mixing model suggested that invertebrates comprised nearly 25% of the diet of of both age‐1 and age‐2 individuals. The relationship between Colorado pikeminnow size and δ¹⁵N within stocked cohorts indicated that juveniles slowly transitioned to consuming fish prey as they grew, rather than abruptly switching, as indicated from a limited number of dietary studies using wild fish. • Together, these results suggest that Colorado pikeminnow stocked into the San Juan River slowly transition to consuming fish prey. If this pattern leads to poor survival and recruitment, the effectiveness of this management action for conservation could be compromised.
... The Murray River population appears to be more abundant than originally thought with evidence of expansion. Wild recruitment has been detected in a number of catchments (Goulburn, Ovens, Mid and Upper Murrumbidgee, Cotter) between the late 1990s and mid 2000s (Lyon et al., 2012;Koehn et al., 2013). Comprehensive monitoring of the lower Ovens River demonstrated the benefits of a long-term stocking program, with wide variation in the contribution of individual stocking events to the resultant population (Lyon et al., 2012). ...
... Wild recruitment has been detected in a number of catchments (Goulburn, Ovens, Mid and Upper Murrumbidgee, Cotter) between the late 1990s and mid 2000s (Lyon et al., 2012;Koehn et al., 2013). Comprehensive monitoring of the lower Ovens River demonstrated the benefits of a long-term stocking program, with wide variation in the contribution of individual stocking events to the resultant population (Lyon et al., 2012). Genetic analysis of upper Murrumbidgee cod larvae from 2011 -2013 found hybridization between Trout cod and Murray cod, (Couch et al., 2016) demonstrating the problem of re- establishing a threatened species into the range of an established congeneric. ...
... The Murray River population appears to be more abundant than originally thought with evidence of expansion. Wild recruitment has been detected in a number of catchments (Goulburn, Ovens, Mid and Upper Murrumbidgee, Cotter) between the late 1990s and mid 2000s (Lyon et al., 2012;Koehn et al., 2013). Comprehensive monitoring of the lower Ovens River demonstrated the benefits of a long-term stocking program, with wide variation in the contribution of individual stocking events to the resultant population (Lyon et al., 2012). ...
... Wild recruitment has been detected in a number of catchments (Goulburn, Ovens, Mid and Upper Murrumbidgee, Cotter) between the late 1990s and mid 2000s (Lyon et al., 2012;Koehn et al., 2013). Comprehensive monitoring of the lower Ovens River demonstrated the benefits of a long-term stocking program, with wide variation in the contribution of individual stocking events to the resultant population (Lyon et al., 2012). Genetic analysis of upper Murrumbidgee cod larvae from 2011 -2013 found hybridization between Trout cod and Murray cod, (Couch et al., 2016) demonstrating the problem of reestablishing a threatened species into the range of an established congeneric. ...
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https://portals.iucn.org/library/node/47668
... The Murray River population appears to be more abundant than originally thought with evidence of expansion. Wild recruitment has been detected in a number of catchments (Goulburn, Ovens, Mid and Upper Murrumbidgee, Cotter) between the late 1990s and mid 2000s (Lyon et al., 2012;Koehn et al., 2013). Comprehensive monitoring of the lower Ovens River demonstrated the benefits of a long-term stocking program, with wide variation in the contribution of individual stocking events to the resultant population (Lyon et al., 2012). ...
... Wild recruitment has been detected in a number of catchments (Goulburn, Ovens, Mid and Upper Murrumbidgee, Cotter) between the late 1990s and mid 2000s (Lyon et al., 2012;Koehn et al., 2013). Comprehensive monitoring of the lower Ovens River demonstrated the benefits of a long-term stocking program, with wide variation in the contribution of individual stocking events to the resultant population (Lyon et al., 2012). Genetic analysis of upper Murrumbidgee cod larvae from 2011 -2013 found hybridization between Trout cod and Murray cod, (Couch et al., 2016) demonstrating the problem of reestablishing a threatened species into the range of an established congeneric. ...
Book
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This sixth edition of the Global Reintroduction Perspectives provides 59 case studies covering invertebrates, fishes, amphibians, reptiles, birds, mammals and plants. We hope the information presented in this book will provide a broad global perspective on challenges facing reintroduction projects trying to restore biodiversity.
... Various management interventions have been applied in an attempt to conserve imperilled fish species and populations, with captive breeding and stocking commonly employed (e.g. Lyon et al. 2012). However, the limitations of such approaches are becoming more widely appreciated, with considerable knowledge of the target species reproductive biology required, concerns about hatchery domestication and genetic diversity, and increasing evidence of behavioural changes and reduced fitness of hatchery-bred individuals (Philippart 1995;Brown and Day 2002;Ebner et al. 2007;Frankham 2008). ...
... Even for projects at small spatial scales, the challenge of maintaining continuity of data collection over extended timeframes is rarely met. Reintroduction science is characterised by small population sizes, with all of the contingent problems caused by stochastic processes in variable environments (Weeks et al. 2011;Lyon et al. 2012). Consequently,although many reintroductions are claimed as 'successes', such claims can be ephemeral and the establishment of self-sustaining populations does not necessarily equate to population persistence (Seddon 1999). ...
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Translocation is an increasingly popular conservation management activity worldwide, but the success of translocation is often not measured or reported. A population of the endangered Macquarie perch was imperilled by the damming in 1977 of the Queanbeyan River, near Canberra in south-eastern Australia. In November 1980, 66 adult Macquarie perch (309-389-mm total length) individuals were collected from the newlyformed reservoir, and translocated approximately 4km upstream into the Queanbeyan River past a waterfall (which prevented access to spawning habitat). Five years of post-translocation monitoring at the release sites resulted in the capture of only a single individual in late 1981. Consequently, monitoring ceased because the translocation was assumed to have failed. However, subsequent angler reports and a preliminary survey in 1991 confirmed that some translocated fish had survived, and a small recruiting population had established. More intensive follow-up surveys and subsequent monitoring from 1996 to 2006 demonstrated an established population with consistent recruitment until 2001. However, after 2001, there was no evidence of recruitment and the population is now undetectable, with the prolonged 'millennium drought' (1997-2010) being the most plausible cause. The present study demonstrates the potentially ephemeral nature of assessments of success and failure, and the importance of targeted long-term monitoring programs. Journal compilation
... Briefly, thin transverse sections of either the left or right sagittal otolith from each fish were mounted on a glass slide and examined under a stereo microscope with transmitted light, independently labelled and photographed at 920 magnification. Counts of annuli, defined as a pair of translucent and opaque zones, were determined by staff experienced in otolith preparation and interpretation, as has previously been conducted for each of the study species (Anderson et al., 1992a, b;Mallen-Cooper & Stuart, 2003Lyon et al., 2012. ...
Article
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Fish are often targets for environmental watering outcomes under the premise that aspects of the flow regime are linked to key components of their life-history. This study examined the conceptual link between variability in river discharge and fish productivity by measuring annual growth patterns (generated using sclerochronology over a 22-year period) of two native freshwater cod Maccullochella spp. species over a range of flow conditions in a regulated Australian floodplain River. We found a positive relationship between fish growth, flow variability and river discharge. Flow variability during spring and summer-autumn, as well as their antecedent values, was particularly important in explaining annual growth of the nationally endangered Maccullochella macquariensis. Growth of Maccullochella peelii displayed similar patterns, though were more closely aligned with spring discharge. These results are consistent with the general view that increased river regulation, due to its suppression of flow magnitude and variability, has been a major contributing factor in the decline of native fish populations throughout the world. Our results provide support and guidance for the use of environmental water delivery, and have broad application to rivers worldwide for which any quantification of ecological impacts of regulation, and responses to water management remain scarce.
... It is essential that any reintroduction strategy have an associated monitoring program, and as conservation translocations are usually a long-term commitment, the monitoring program should reflect this (IUCN/SSC, 2013). Determining the success of translocations can be difficult to define and ephemeral (Seddon, 1999;Lintermans, 2013b) but is often defined as the establishment of a reproducing population (e.g., Lyon et al., 2012). The detectability of different age classes of Macquarie perch (e.g., adults, young of year and juveniles) varies with sampling method, with the presence of YOY and age 1+ individuals able to be determined with a high degree of confidence, but the detectability of adults is much less certain (Lintermans, 2013b). ...
Article
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The number of threatened species continues to increase due to a range of anthropogenic disturbances, and many species continue to decline increasing their risk of extinction. Translocation is a widely used management technique to establish new populations to reduce the risk of extinction. There are, however, a range of issues to be considered. For example, for some species the donor population may be impacted by translocation, for other species it must be decided whether to translocate adults or juveniles to establish new populations. The question then becomes who do you move? The endangered Macquarie perch in south-eastern Australia is continuing to decline, with the recent Millennium Drought (1997–2010) and associated events (e.g., bushfires) contributing to dramatic local declines and the need for emergency responses. Successful historic translocations of this species involved adult fish, however the removal of significant numbers of adult fish may now impact source populations and alternative translocation approaches needed investigating. The use of sub-adult or juvenile fish, that would be expected to experience higher mortality, may be an approach to establishing new populations which would have less severe impacts on source populations. However, the number of fish required, frequency of translocation and likelihood of population establishment are unknown. This study outlines the development of a population model to assist in trialling translocation scenarios for establishing new populations of Macquarie perch. The model predicts that translocations of young-of-year fish (age 0+) is unlikely to be successful unless ∼600 females are released annually for five years. If translocating yearling (age 1+) fish, annual translocations of >100 females is required to achieve success, with stocking for at least five consecutive years required. If the frequency of recruitment failure or magnitude of Allee effects increases, then translocations of increased numbers of yearlings or prolonged stocking (10 years) is required to achieve success. The addition of small numbers of adult fish in combination with yearlings decreases the number of yearlings required, and increases the chance of success under more stressful scenarios.
... Management actions are used to restore disturbed habitats and stabilize populations of endangered species (Kodric-Brown and Brown, 2007), and have been shown to be a viable solution in promoting the recolonization of desert fishes (Scoppettone et al., 2005). At a global scale, most reintroductions of threatened and endangered fish species have produced little success (Lyon et al., 2012), but there are some exceptions. For example, stable population growth of flannelmouth suckers (Catostomus latipinnis) was achieved after introduction into the Colorado River downstream from formerly used habitats to mitigate effects of dam construction (Mueller and Wydoski, 2004). ...
Article
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Choosing an optimal strategy to sustain imperilled wild populations is challenging, and many methods may be implemented before reaching an effective strategy. A review of previous conservation efforts used to maintain an endangered desert pupfish (Cyprinidon bovinus) are presented here. Conservation strategies for C. bovinus have included removal of fish hybridizing with a non-native species, reintroduction of captive-bred C. bovinus into their historic range, and habitat restoration and expansion. In general, these methods have successfully increased the C. bovinus population over a 15-year period, with habitat expansion appearing to be the most critical intervention method. Habitat restorations that increased the available breeding habitat for C. bovinus and the total number of breeding males were also associated with a downward trend in individual male reproductive behaviour. Since habitat expansion resulted in unexpected consequences for reproductive ecology, it emphasizes the importance not only of monitoring species abundance but also of evaluating individual reproductive behaviour when implementing conservation strategies.
...  Increaseng woody habitats in key areas combined with the implementation of species specific recovery flows based on key aspects of site-specific, natural flow regimes. E.g. high winter / early spring flood-or flow-pulses to cue spawning migration, dispersal, habitat enhancement and productivity  Fund recovery teams and implement recovery plans  Design Tonkin et al. (2009); National Murray Cod Recovery Team (2010a,b); Tonkin et al. (2010a); Balcombe et al. (2011); King et al. (2011); Kearns et al. (2012); Lyon et al. (2012); Baumgartner et al. (2013); Lintermans (2013); Barwick et al. (2014) A key issue is river regulation and water extraction (river and groundwater) influencing the amount and quality of inflows (i.e. water levels) available to floodplain, riverine and lake habitats. ...
... In recent years a number of models have been developed for Australian native freshwater fish. A population viability analysis of Trout Cod by Todd et al. (2004) examined some key uncertainties and provided useful strategies for reintroduction, which were later successfully implemented in the Ovens River (Lyon et al. 2012). Todd et al. (2005) examined the threatening process of cold-water releases on Murray Cod and developed a case study for the Mitta Mitta River, explaining the decline of Murray Cod in that system. ...
... Stocking of native fish over multiple years, rather than in a once only event, has been promoted to build up a structured population, increase genetic diversity and to overcome unseasonal or unpredictable (catastrophic) events impacting on survival (Douglas et al. 1994). The effective of this approach was demonstrated in the decade-long Ovens River trout cod stocking program in which fish stocked in 2003 and 2004 were more common than fish stocked in other years, indicating a higher rate of survival for the fish released in these years (Lyon et al. 2012). ...
... One conservation objective of the latter is to "Investigate the use of re-introductions of freshwater catfish to improve the status of the species, and initiate at least two reintroductions into appropriate sites within Victorian waters". This approach has been applied to other threatened species (Rinne et al. 1986, Ingram et al. 1990, Rowland 2013, and has been particularly successful for trout cod (Ingram and Thurstan 2008, Lyon et al. 2012, Koehn et al. 2013. ...
Technical Report
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Freshwater catfish (Tandanus tandanus) is a popular freshwater angling species in rivers of the Murray-Darling Basin (MDB). In recent decades the species has, however, undergone substantial declines in abundance and distribution. In Victoria, freshwater catfish is listed as threatened under the Flora and Fauna Guarantee Act 1988, occurring in small isolated populations only. In 2011, Native Fish Australia (NFA), (Wimmera) Inc. received funds from the Department of Primary Industries’ Recreational Fishing Grants Program to help restore Victoria’s recreational fishery by captive breeding and re-stocking freshwater catfish. The aim of this study was to observe spawning trials on freshwater catfish to produce juveniles for restocking into Victorian waters. Spawning trials focused on use of Ovaprim® to induce ovulation and spermiation in fish that where hand-stripped, and Ovaplant® (Syndel, Canada) to enhance maturation and ovulation in fish allowed to spawn naturally. Nineteen females and 26 males were used in spawning trials conducted in late October 2013, when water temperatures approached 20oC. Tetrauronema, a new myxozoan parasite of freshwater catfish, was observed in a milt sample from one fish. The implications of the presence of this parasite in freshwater catfish is unknown. Most females (70%) injected with Ovaprim were induced to spawn. Broodstock implanted with Ovaplant and transferred to a 0.15 ha pond containing patches of gravel subsequently spawned naturally within a month of being implanted. Small amounts (0.1-1.0 mL) of milt, which was generally watery in consistency, was stripped from males. There was a slight improvement in both milt consistency and sperm activity 2 days after injection with hormones. Relative fecundity of stripped females was low (920-3,370 eggs/kg). Although fertilisation rates (65-100%) were generally high, hatch rates (0-42%) were low and a high proportion (10-20%) of larvae were deformed. These results suggest that not all oocytes in the ovary were mature and consequently, responded to the hormone treatment, and/or fish were not fully conditioned for spawning. Spawning trials are likely to have occurred at the very beginning of the spawning season and so fish may not have been fully mature, which may affected fecundity, gamete quality, hatch rates and larval quality. Fry were reared to fertilised earthen pond, and on 7th February 2014, 1,900 fingerlings were harvested, 1,400 of these were released into Moodemere Lake (Rutherglen) and 500 into Crusoe Reservoir (Bendigo). Observations made during these trials will be used to guide future R&D to improve captive breeding of freshwater catfish. Recommendations include: • Increase broodstock numbers to increase productivity • Reduce broodstock densities in ponds to optimise growth, conditioning and maturation • Supplement the diet of broodstock with live prey (small yabbies) • Remove the fish infected with Tetrauronema to reduce the risk of spreading the disease to other stock • Check for the presence of this parasite in other broodstock during the next spawning season • Undertake induced spawning later in the season, once water temperatures exceed 21oC and before reach 25oC (i.e. early to mid-November) • Inject females and males to be hand-stripped each with a single doses of Ovaprim at 0.5 ml/kg • Repeat natural spawning trials to obtain further information on production levels for comparison with to induced spawning and hand-stripping methods • Rear fry into a pond by themselves using standard fry rearing methods employed for other native fish species.
... This result suggests that repeated stocking improves establishment probability, as has been found in other studies (Hilderbrand 2002;Sheller et al. 2006). If fish are stocked annually for several years, they may be more likely to encounter a favorable year for survival or reproduction (Lyon 2012). Population modeling of cutthroat trout (Onchorhynchus clarki) shows that stocking in multiple years can compensate for other stocking practices (e.g., low number stocked, small size of stocked fish) that might otherwise reduce probability of population persistence (Hilderbrand 2002). ...
Article
Reintroduction of imperiled native freshwater fish is becoming an increasingly important conservation tool amidst persistent anthropogenic pressures and new threats related to climate change. We summarized trends in native fish reintroductions in the current literature, identified predictors of reintroduction outcome, and devised recommendations for managers attempting future native fish reintroductions. We constructed random forest classifications using data from 260 published case studies of native fish reintroductions to estimate the effectiveness of variables in predicting reintroduction outcome. The outcome of each case was assigned as a success or failure on the basis of the author's perception of the outcome and on whether or not survival, spawning, or recruitment were documented during post-reintroduction monitoring. Inadequately addressing the initial cause of decline was the best predictor of reintroduction failure. Variables associated with habitat (e.g., water quality, prey availability) were also good predictors of reintroduction outcomes, followed by variables associated with stocking (e.g., genetic diversity of stock source, duration of stocking event). Consideration of these variables by managers during the planning process may increase the likelihood for successful outcomes in future reintroduction attempts of native freshwater fish. Identificación de Correlaciones de Éxito y Fracaso de Reintroducciones de Peces de Nativos Agua Dulce.
... As is the case with habitat restoration, releasing individuals back into the wild is not a straightforward process, as a multitude of factors including food acquisition, predator avoidance, and acclimation to the natural habitat all must be taken into consideration for the successful establishment and persistence of a reintroduced population [1]. The successful reintroduction of species is rare across taxa [16], and additional work is needed in order to monitor those that have been released [13], as well as develop new strategies to ensure maximum species survival upon reintroduction. However, some reintroduction efforts, including populations of threatened and endangered fishes, have shown signs of success through their stable population growth [14,15]. ...
Article
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The Leon Springs pupfish (Cyprinodon bovinus) is an endangered fish endemic to Diamond Y Spring in west Texas. To mitigate the negative effects of habitat loss, Diamond Y Spring was renovated to maintain and provide additional breeding habitat. Monsanto Pool, an extant location where C. bovinus have become extirpated, was also renovated in order to increase breeding habitat. After Monsanto Pool was renovated, captive-bred C. bovinus were reintroduced to this location to both increase the range of this species, and evaluate whether captive release is a viable option. These conservation efforts have led to the unique opportunity to evaluate the efficacy of habitat renovations in wild and captive-bred populations of C. bovinus, occurring in natural and renovated breeding habitats at two separate locations. The overarching question asked was, is it better to renovate an unoccupied site and introduce captive-bred individuals, or to expand an occupied site that would allow the current population to grow? Habitat use and spawning in three different breeding areas were compared, and specific ecological factors were measured at each site in order to determine if any coincided with observed C. bovinus location preferences. Wild C. bovinus in the natural breeding habitat spawned more, had more spawns per individual male, and had greater territorial stability than wild or captive-bred C. bovinus in renovated habitats. Differences in social system stability and reproductive success between sites may be due to variation in their ability to adapt to a renovated site as well as the ecological makeup of the habitat.
... Further, there are a variety of concerns for hatchery programs around domestication and genetic integrity (Brown and Day 2002;Nock et al. 2011). While captive husbandry has a significant role in the management of many threatened species, and if well managed can produce positive results (see Lyon et al. 2012;Koehn et al. 2013), it must be viewed as only one component of a broader recovery program, with in situ responses preferred (Lintermans 2013a). ...
... (Rowland 1998a) have been reported. Lyon et al. (2012) reported more females than males (♀ : ♂ 2.5:1) in a population of trout cod stocked from hatchery bred fish. ...
... As with reintroductions involving many other taxon, most efforts to reintroduce imperiled fishes have not been adequately documented or monitored following implementation and it is often difficult to evaluate whether they were successful (Dunham, Gallo, Shively, Allen, & Goehring, 2011;Williams, Sada, & Williams, 1988). Despite this, evidence exists indicating some reintroduction efforts involving fish have succeeded while others have failed (Lyon et al., 2012;Reading, Clark, & Kellert, 2002). ...
Article
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Abstract Bull trout in the Wallowa River watershed were considered extirpated in the 1950s. In 1997, bull trout from the adjacent Imnaha River watershed were reintroduced into the Wallowa River watershed. We evaluated whether bull trout are currently present in the Wallowa River watershed and, if so, whether they appear to be the result of the 1997 reintroduction. From 2010 to 2018, we captured 181 Salvelinus spp. The majority (64.5%) of these individuals were bull trout. Bull trout in the Wallowa River watershed were more genetically similar to those from the Imnaha River watershed (pairwise FST = 0.102) than to the other populations we examined. They also exhibited genetic evidence of a recent bottleneck (observed heterozygosity was 0.598, significantly greater than expected). Modeled estimates of size (541–581 mm), survival (
... localised release sites, islands and exclosures), the lack of longer temporal scales in many aquatic reintroduction activities gives cause for concern (Lintermans 2013c). Lyon et al. (2012) demonstrated that, after a decade of repeated releases of trout cod, recruitment of juveniles only occurred in a small subset of years, indicating that short temporal scale interventions may not encounter environmental conditions that promote success. ...
... Substantial sampling effort over the period 2008-2011 , Wedderburn and Barnes 2009, Bice et al. 2010, Wedderburn and Hillyard 2010, 2012, Whiterod and Hammer 2014 suggesting a low number of individuals remained in wild habitats. Given the species high mobility and tolerance to elevated salinity abundance may occur. ...
... Once re-established through stocking, environmental watering may then be used to support their essential life history requirements. The solution is simple: construct a hatchery for threatened fish, commence commercial scale production, reintroduce fish into key sites (ideally following removal of carp to prevent competition; Figure 2f), and then deliver environmental water in a manner that enables fish to reproduce, spawn, and expand their distributions Lyon et al., 2012). Techniques to propagate species such as Murray cod, golden perch (Macquaria ambigua ambigua), silver perch (Bidyanus bidyanus), eel-tailed catfish, trout cod (Maccullochella macquariensis), southern purple spotted gudgeon, southern pygmy perch, and Macquarie perch (Macquaria australasica) are well established (Lake, 1967a(Lake, , 1967bRowland, 1989). ...
Article
Restoration programmes for degraded aquatic ecosystems frequently focus on flow restoration or reinstatement, including recovery targets for volumes of water to be used for environmental benefit. Australia's Murray–Darling Basin is an example of a major system undergoing substantial water reform to balance the needs of competing users, including the environment, within the constraints of an arid climate. This reform revolves around accounting for finite volumes of water that have been shared amongst water users. We argue that while recovering water will provide good outcomes, as a sole intervention, it is not enough to deliver the desired environmental benefits of the reform given the significantly altered state of the catchment. Here, we present 10 measures that could be used to complement planned water recovery actions. These “complementary measures” integrate recovery actions, which when strategically combined with water delivery would significantly enhance water reform efforts to generate environmental outcomes in a highly modified system.
... Over the past two decades, strict fishing regulations have been applied, and major habitat rehabilitation of the Ovens River included livestock removal, restoring riparian revegetation and in-stream woody habitat, pest control and reintroduction of another extirpated threatened fish species (Department of Environment, Land, Water and Planning, 2017;Lyon et al., 2012). ...
Article
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Through using different sources, population reintroductions can create genetically diverse populations at low risk of harmful inbreeding and well‐equipped for adaptation to future environments. Genetic variation from one source can mask locally non‐optimal alleles from another, thereby enhancing adaptive potential and population persistence. We assessed the outcomes in survival, growth and reproduction of using two differentiated sources (genetically diverse Yarra and moderately diverse Dartmouth) for translocations and stocking to reintroduce the endangered Australian freshwater Macquarie perch Macquaria australasica into the Ovens River. For stocking, same‐ and different‐population parents (‘cross‐types’) were used during hatchery production. Genetic samples and data on individual fish were collected over three years of monitoring the Ovens. We genetically assigned Ovens fish to their broodstock parents and tested whether cross‐type and genetic dissimilarity between parents are associated with offspring survival, and whether cross‐type and parental dissimilarity or individual genetic diversity are associated with somatic growth rates of stocked fish. We genetically identified translocated fish and assessed local recruit ancestry. Of 296 Ovens fish, 31.1% were inferred to be stocked, 1.3% translocated and 67.6% locally‐born. Cross‐type strongly predicted survival of stocked offspring: those with two Yarra parents had the highest survival, followed by offspring with two‐population, then Dartmouth, ancestry. Of the Ovens recruits, 59.5% had Yarra, 33.5% two‐population, and 7.0% Dartmouth ancestry, despite 67% of stocked and 98% of translocated fish originating from Dartmouth. Offspring with two Yarra parents grew faster than offspring of Dartmouth or two‐population ancestry. Although Dartmouth fish appear to be less fit in the Ovens compared to Yarra fish, possibly due to deleterious variation or genetic or plastic maladaptation, they contribute to the reintroduced population through local interbreeding with Yarra fish and relatively high survival of stocked offspring of two‐population ancestry. Thus, combining compatible stocks is likely to benefit restoration of other wildlife populations.
... Translocated individuals may be either captive-bred or sourced from existing wild populations (Faria et al., 2010;Hammer et al., 2013;Seddon et al., 2012). Typically, programmes involving captive-bred fish have the capacity to reintroduce levels-of-magnitude more individuals than wild to wild efforts (Hayes & Banish, 2017;Ingram et al., 2011;Lyon et al., 2012), although maintaining fish in captivity requires significant effort. Using wild fish as a source for translocation generally means fewer fish may be moved, especially for threatened species with small populations, although this approach is still effective. ...
Article
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Stocky galaxias Galaxias tantangara is a newly‐described freshwater fish restricted to a single population, occupying a 3 km reach of a small headwater stream in the upper Murrumbidgee River catchment of south eastern Australia. Listed as critically endangered under IUCN Red List criteria, knowledge of the species’ ecology is critical for future conservation efforts to establish additional populations by translocation and captive breeding. This study details the first account of spawning and reproductive ecology of G. tantangara, including reproductive development, timing of spawning and a description of one spawning site. Peak gonadosomatic index was observed in March/April in males and October in females. Absolute fecundity ranged from 211 oocytes for a 76 mm LCF fish, to 810 oocytes for a 100 mm LCF fish. The observation of spent females in mid‐November 2017, and discovery of an egg mass eight days later suggests spawning had occurred, and over a relatively short period. Larvae were subsequently detected in monthly electrofishing surveys in December 2017. Findings from this study provide new understanding of existing and future threats to G. tantangara and has important implications for conservation management of not only this species, but also other closely related threatened Galaxias species. This article is protected by copyright. All rights reserved.
... Well-known examples of successful captive-breeding and (re)introduction programmes include, for instance, Przewalski's horse Equus caballus przewalski in Mongolia (Kaczensky et al. 2011), California condor Gymnogyps californianus (Walters et al. 2008), Iberian lynx Lynx pardinus in Spain (Simón et al. 2012), bearded vultures Gypaetus barbatus in the Alps (Schaub et al. 2009) and in Spain (Bustamante 1998), Arabian oryx Oryx leucoryx in the Arabian peninsula (Spalton et al. 1999), dorcas gazelle Gazella dorcas neglecta in Senegal (Abáigar 2010) or Australian trout cod Maccullochella macquariensis (Lyon et al. 2012), among many others. It is important to remark that the release of specimens of captive animals should not be considered a long-term conservation strategy. ...
Article
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Modern zoos actively collaborate in the conservation of many endangered species by captive breeding for reintroduction. This paper presents the reproductive success of a captive colony of northern bald ibis Geronticus eremita (NBI) at ZooBotánico de Jerez between 1993 and 2013 (21 years). Between 2004 and 2011 was "Proyecto Eremita", a study of the best releasing techniques for hand-reared NBI in Cadiz in order to establish a free-range, self-sustained population in the wild. During this period, first-clutch eggs were artificially incubated and chicks were hand reared until fledgling stage, allowing the pair to produce a second or replacement clutch that was parent reared. This paper compares the colony's reproductive success between the years where one single clutch was reared by the pairs (n=13) and the years of Proyecto Eremita (n=8), with two clutches, the first hand reared and the second parent reared. The reproductive success rate was measured in 300 nests. A total of 268 fledglings reached 2 months old, the age considered here as the reproductive success. Two reproductive variables were significantly higher during the Proyecto Eremita years: mean number of fledglings per nest (1.8 versus 0.3) and overall number of fledglings recorded per year (26.5 versus 4.3). The reproductive success of hand-reared clutches was similar to parent-reared clutches. There was a significant and negative effect of colony size on the percentage of birds paired and on reproductive success. Parent-reared clutches during the Proyecto Eremita showed a higher reproductive success compared to parent-reared clutches outside this period. The data show that a remarkably high percentage of mating pairs outside of the Proyecto Eremita period failed at reproduction, probably due to density-dependent effects. The combination of hand-rearing and parent-rearing methods used in this study was a very effective tool to significantly increase the number of fledglings produced for the reintroduction programme.
... For example, knowledge of critical habitat for the Critically Endangered Leadbeater's possum (Gymnobelideus leadbeateri) lead to the identification and subsequent protection of 50 new colonies of the species (Nelson et al. 2015;Nelson et al. 2017). Similarly, a concerted effort to increase ecological knowledge lead to the development of a successful restocking regime that contributed to the conservation of the endangered trout cod (Maccullochella macquariensis; Lyon et al. 2012;Koehn et al. 2013). ...
Article
A comprehensive and contemporary understanding of habitat and resource requirements has been critical to the conservation of multiple taxa and ecosystems globally. Until recently, much of the ecological knowledge that contributes to conservation priorities and strategies for the Critically Endangered western ringtail possum (Pseudocheirus occidentalis) was largely derived from decades‐old observations in peppermint (Agonis flexuosa) and marri‐jarrah (Corymbia calophylla and Eucalyptus marginanta) woodlands in the northern parts of the species range. These observations do not account for more recent evidence of their flexible use of habitat resources in other regions of its range. This may represent a significant conservation opportunity for the species through the identification of additional habitats that warrant protection. In a region where knowledge of their ecology is scarce, we used scat analysis and quantitative spotlighting to determine the diet and density of western ringtail possums in three vegetation types: peppermint, sheoak (Allocasuarina fraseriana) and marri‐eucalypt (C. calophylla, E. marginanta and Eucalyptus staerii) woodlands. Given the species’ reported dependence on peppermint woodlands and dominant canopy species for food sources, we hypothesised that western ringtail possums would be most abundant in this habitat type and that their diet would comprise the foliage of few (≤2 species) canopy species. We found western ringtail possums consumed a higher diversity of plant species than expected (8–14), exhibited dietary preference for non‐dominant canopy species and were present in all sampled vegetation types at substantially higher densities than previously recorded for the region (as high as 17 possums ha−1). Our results confirm (i) the western ringtail possum is flexible in its use of habitat resources and (ii) the significant conservation value of sheoak and marri‐eucalypt woodlands in the southernmost portion of its distribution.
... Evidence of successful translocations of imperilled species back into their indigenous ranges is rarely documented across taxa (Fischer & Lindenmayer, 2000;Reading, Clark, & Kellert, 1991;Wolf, Griffith, Reed, & Temple, 1996); however, efforts to reintroduce fish have shown signs of success (Cochran-Biederman, Wyman, French, & Loppnow, 2015;Lyon et al., 2012;Mueller & Wydowski, 2004;Shute, Rakes, & Shute, 2005). This may explain why translocations of imper- illed species of fish, from artificial breeding areas back to their natural habitats, have become extremely common (George, Kuhajda, Williams, & Shute, 2009;Philippart, 1995;Shute et al., 2005). ...
Article
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• Translocation of endangered species from captivity into the wild is a common conservation practice used to bolster populations, expand natural ranges, and restore species that have been extirpated. • Often little is known of the fate of organisms after they are released, and extended monitoring of reintroduced populations is necessary for understanding the efficacy of this method. • Thought to have become extinct, the endangered Leon Springs pupfish (Cyprinodon bovinus) was rediscovered in 1965. Recently, conservation efforts have focused on renovating their natural habitat and reintroducing C. bovinus from a captive colony established in 1976 back into the ancestral habitat. • A reintroduction was performed in 2015, and the population was monitored over the next 14 months to ascertain whether territorial males were behaving typically for the species, and whether there were any changes in social behaviour over time. • An established population in nearby Diamond Y Spring was used as a benchmark for typical social behaviour, and as an indicator for any expected seasonal differences in behaviour. • The development of a typical social system at Monsanto Deep Pool was evident almost immediately, as males started to establish breeding territories, defend them from intruders, and participate in reproductive activities, such as courtship and spawning. The presence of juveniles within a year indicated that individuals were successfully reproducing. • It appears that the translocated C. bovinus are developing into a stable and reproductively successful population.
... The species has undergone declines in distribution and abundance to the extent that it is now listed as nationally Endangered under the Commonwealth Environment Protection and Biodiversity Conservation (EPBC) Act 1999. Trout cod currently occupy a range of habitats, but are naturally riverine and strongly associated with large woody instream habitats (Lyon et al., 2012;Nicol, Barker, Koehn, & Burgman, 2007). As such, habitat degradation and river regulation are thought to be major drivers of their decline (Koehn et al., 2013;Lintermans, 2009). ...
Article
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• Conservation strategies for endangered species often include protection from harvest by humans. Correct species identification is paramount for this form of management to be effective. • Trout cod (Maccullochella macquariensis) is a threatened Australian freshwater fish, occupying habitats in the southern Murray–Darling basin. Trout cod, although protected from angling, morphologically resemble Murray cod (Maccullochella peelii), a species that is a key target of recreational anglers. • During a long‐term mark–recapture study, angler return data were collected both for Murray cod and trout cod. • Up to 40% of trout cod captured were identified by anglers as Murray cod, and the chance of misidentification increased with the increasing size of trout cod, implying that this species could be inadvertently retained by anglers. Moreover, unnecessary angling mortality of adult breeding individuals is likely to delay the time for recovery of this threatened species. • As a large and vocal user group, anglers can play a key role in promoting the conservation of aquatic areas and fish species. There is a need for anglers and fishery managers to understand this problem and to work together on a solution, through the tighter enforcement of regulations where trout cod are present, and through an increased emphasis on education.
... In recent years, several case studies have provided convincing evidence of successful reintroductions, which offer a solid hope of success in the case of the mountain bongo. Key examples include the black-footed ferret (Mustela nigripes) (Jachowski et al. 2011), the golden lion tamarin (Leontopithecus rosalia) (Kierulff et al. 2013), the Puerto Rican crested toad (Peltophryne lemur) (Beauclerc et al. 2010), African wild dogs (Lycaon pictus) (Gusset et al. 2010), the Australian trout cod (Maccullochella macquariensis) (Lyon et al. 2012) and the Arabian oryx (Oryx leucoryx) (Islam et al. 2011). ...
... The stocking-strategy and adaptive-management approach outlined by and Todd et al. (2004) for trout cod has been successful for some populations. Lyon et al. (2012) postulated that an important facet of a long-term stocking program for recovery of an endangered species is the increased chance of a stocked cohort encountering favourable environmental conditions that promote local survival, particularly immediately following release. In the Ovens River, fish stocked in 2003 and 2004 were more highly represented in sampling programs than those from other years, supporting the conservative approach of releasing stock over a longer period of time . ...
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Recovery of threatened species is often necessarily a long-term process. The present paper details the progress towards the recovery of trout cod, Maccullochella macquariensis, an iconic, long-lived fish species first listed as threatened in the 1980s. The objectives, actions and progress over three successive national recovery plans (spanning 18 years) are assessed, documenting changes to population distribution and abundance and updating ecological knowledge. Increased knowledge (especially breeding biology and hatchery techniques, movements, habitats and genetics) has greatly influenced recovery actions and the use of a population model was developed to assist with management options and stocking regimes. Key recovery actions include stocking of hatchery-produced fish to establish new populations, regulations on angling (including closures), education (particularly identification from the closely related Murray cod, M. peelii) and habitat rehabilitation (especially re-instatement of structural woody habitats). In particular, the establishment of new populations using hatchery stocking has been a successful action. The importance of a coordinated long-term approach is emphasised and, although there is uncertainty in ongoing resourcing of the recovery program, much has been achieved and there is cautious optimism for the future of this species
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Stocking of native fishes is conducted to augment riverine fisheries in many parts of the world, yet most stocking activities are conducted without empirical information on their effectiveness or impacts. In the Murray–Darling Basin (MDB), Australia, stocking has been underway for several decades to maintain recreational fisheries. We stocked chemically tagged golden perch (Macquaria ambigua) fingerlings in three rivers to determine the proportions of stocked fish within populations of the species. Stocked sites were monitored for up to 5 years in the Murrumbidgee River, Edward River and Billabong Creek and non-stocked sites were monitored in the Murray River. Catch per unit effort of stocked year classes increased substantially in Billabong Creek, with stocked fish contributing 100 (2005), 79 (2006) and 92% (2007). Chemically tagged fish comprised 18–38% of the respective age classes in the Murrumbidgee and Edward rivers and there was little evidence of natural recruitment in the non-stocked Murray River. Tagged fish generally attained the legal minimum size within 4 years and had dispersed up to 60 km from the original release location. Our results demonstrate that artificial stocking has the potential to strongly influence the abundance and population structure of golden perch in rivers of the MDB.
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• In many animal populations, demographic parameters such as survival and recruitment vary markedly with age, as do parameters related to sampling, such as capture probability. Failing to account for such variation can result in biased estimates of population‐level rates. However, estimating age‐dependent survival rates can be challenging because ages of individuals are rarely known unless tagging is done at birth. For many species, it is possible to infer age based on size. • In capture–recapture studies of such species, it is possible to use a growth model to infer the age at first capture of individuals. We show how to build estimates of age‐dependent survival into a capture–mark–recapture model based on data obtained in a capture–recapture study. • We first show how estimates of age based on length increments closely match those based on definitive aging methods. In simulated analyses, we show that both individual ages and age‐dependent survival rates estimated from simulated data closely match true values. With our approach, we are able to estimate the age‐specific apparent survival rates of Murray and trout cod in the Murray River, Australia. • Our model structure provides a flexible framework within which to investigate various aspects of how survival varies with age and will have extensions within a wide range of ecological studies of animals where age can be estimated based on size.
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Rates of hybridization and introgression are increasing dramatically worldwide because of translocations, restocking of organisms and habitat modifications (Allendorf et al., 2001) thus determining whether hybridization is beneficial or detrimental for the species involved is commensurately important for conservation. Restocking programs are sometimes criticized because of the genetic consequences of hatchery-bred fish breeding with wild populations. These concerns are important to conservation restocking programs, including Percichthyidae. Two of the better known Australian Percichthyidae are the Murray Cod (Maccullochella peelii) and Trout Cod (Maccullochella macquariensis) which were formerly widespread over the Murray Darling Basin. In much of the Murrumbidgee River Trout Cod and Murray Cod were sympatric until the late 1970s when Trout Cod were extirpated. Here we use genetic SNP data to examine hybridization and introgression between Murray Cod and Trout Cod in the upper Murrumbidgee River and consider implications for restocking programs. For the first time we have confirmed restocked riverine Trout Cod as reproducing in the wild. We detected hybrid Trout Cod-Murray Cod in the Upper Murrumbidgee, recording the first hybrid larvae in the wild. Although hybrid larvae, juveniles and adults have been recorded in hatcheries and impoundments, and hybrid adults have been recorded in rivers previously (Douglas, Gooley & Ingram, 1994a; Douglas et al., 1995) , this is the first time fertile F1 have been recorded in the wild. The F1 backcrosses with Murray cod have also been found to be fertile. All backcrosses noted were with pure Murray Cod. Such introgression has not been recorded previously in these two species, and the imbalance in hybridization direction may have important implications for restocking programs.
Preprint
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Rates of hybridization and introgression are increasing dramatically worldwide because of translocations, restocking of organisms and habitat modifications (Allendorf et al., 2001) thus determining whether hybridization is beneficial or detrimental for the species involved is commensurately important for conservation. Restocking programs are sometimes criticized because of the genetic consequences of hatchery-bred fish breeding with wild populations. These concerns are important to conservation restocking programs, including Percichthyidae. Two of the better known Australian Percichthyidae are the Murray Cod (Maccullochella peelii) and Trout Cod (Maccullochella macquariensis) which were formerly widespread over the Murray Darling Basin. In much of the Murrumbidgee River Trout Cod and Murray Cod were sympatric until the late 1970s when Trout Cod were extirpated. Here we use genetic SNP data to examine hybridization and introgression between Murray Cod and Trout Cod in the upper Murrumbidgee River and consider implications for restocking programs. For the first time we have confirmed restocked riverine Trout Cod as reproducing in the wild. We detected hybrid Trout Cod-Murray Cod in the Upper Murrumbidgee, recording the first hybrid larvae in the wild. Although hybrid larvae, juveniles and adults have been recorded in hatcheries and impoundments, and hybrid adults have been recorded in rivers previously (Douglas, Gooley & Ingram, 1994a; Douglas et al., 1995) , this is the first time fertile F1 have been recorded in the wild. The F1 backcrosses with Murray cod have also been found to be fertile. All backcrosses noted were with pure Murray Cod. Such introgression has not been recorded previously in these two species, and the imbalance in hybridization direction may have important implications for restocking programs.
Preprint
Understanding sex-specific biology can aid conservation management. But understanding genomic sex differences of monomorphic fish species and developing molecular sexing assays is challenged by their diverse sex-determination systems. To facilitate research on Percichthyid fish, predominant in the Australian freshwater biota, we report whole genome sequences and annotations of the endangered Macquarie perch Macquaria australasica and its sister species, the golden perch M. ambigua. To identify sex-linked loci, we conducted whole genome resequencing on 100 known-sex Macquarie perch. In-silico pool-seq comparisons revealed few sex differences, but a 275-Kb SOX-containing scaffold was enriched for gametologous loci- homozygous in females, heterozygous in males. Within this scaffold we reconstructed X- and Y-linked 146-bp haplotypes containing 5 sex-linked SNPs, ~38 Kb upstream of SOX, and developed a PCR-RFLP sexing assay targeting the Y-linked allele of one SNP. We tested this assay in a panel of known-sex Macquarie perch, and smaller panels of three other confamilial species. Amplicon sequencing of 400 bp encompassing the 146-bp region revealed that the few sex-linked positions differ interspecifically, and within Macquarie perch such that its sexing test approached 100% reliability only for the populations used in assay development. Similarly, Macquarie- and golden perch genome-wide DArTseq SNPs revealed different sex-linked loci across non-homologous scaffolds. Overall, we identified 22 sex-linked SNPs in Macquarie perch in a predominantly XX/XY system in which females are homozygous at all 22, and males are heterozygous at 2 or more. The resources here will facilitate multi-locus sexing assays for both species and research on Percichthyid biology.
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Translocation is one of the most commonly proposed management actions for securing and recovering native fish species. However, the success of native fish translocations has varied widely due to several limiting factors, including the presence of nonnative fishes. The Blue River Native Fish Restoration Project involved construction of a fish passage barrier, removal of nonnative fish, translocation of three native fish species (Spikedace Meda fulgida, Loach Minnow Rhinichthys cobitis, and Roundtail Chub Gila robusta), and monitoring to determine the success of these actions. After construction of a physical fish passage barrier, the three focal species were stocked several times upstream of the barrier. Nonnative fish were removed annually using multiple gear types, including spearfishing, backpack electrofishing, and trapping. Monitoring data demonstrated a significant shift in the fish assemblage from one with a substantial component of nonnative fishes to one that was exclusively native fishes. Persistence, reproduction, increased abundance, and dispersal were documented for all three focal species within the study area, meeting criteria for establishment success. All nonnative fishes, including the primary targets of removal efforts—Channel Catfish Ictalurus punctatus and Green Sunfish Lepomis cyanellus—were successfully suppressed, if not eradicated entirely, during the study period. Our results illustrate the importance of long‐term monitoring to track and successfully achieve native fish recovery goals. In addition, our results demonstrate that nonnative fish can be mechanically removed from warmwater streams if initial abundance is low, distribution is restricted, and fish passage barriers are in place. Results from this study may be informative for managers hoping to improve the conservation status of warmwater stream fishes through creation of a fish passage barrier, nonnative species removal, and native fish translocation efforts.
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Arlequin ver 3.0 is a software package integrating several basic and advanced methods for population genetics data analysis, like the computation of standard genetic diversity indices, the estimation of allele and haplotype frequencies, tests of departure from linkage equilibrium, departure from selective neutrality and demographic equilibrium, estimation or parameters from past population expansions, and thorough analyses of population subdivision under the AMOVA framework. Arlequin 3 introduces a completely new graphical interface written in C++, a more robust semantic analysis of input files, and two new methods: a Bayesian estimation of gametic phase from multi-locus genotypes, and an estimation of the parameters of an instantaneous spatial expansion from DNA sequence polymorphism. Arlequin can handle several data types like DNA sequences, microsatellite data, or standard multilocus genotypes. A Windows version of the software is freely available on http://cmpg.unibe.ch/software/arlequin3.
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Species recovery efforts generally focus on in situ actions such as habitat protection. However, captive breeding can also provide critical life history information, as well as helping supplement existing or restoring extirpated populations. We have successfully propagated nine species in captivity, including blackside dace, spotfin chubs, bloodfin darters, and boulder darters. Threatened blackside dace, Phoxinus cumberlandensis, were induced to spawn in laboratory aquaria by exposing them to milt from a reproductively mature male stoneroller, Campostoma anomalum or river chub, Nocomis micropogon. The latter are nest-building minnows, with which Phoxinus may spawn in nature. Eggs are broadcast among gravel and pebbles. Blackside dace individuals reared in captivity were used for translocation. Threatened spotfin chubs, Cyprinella monacha, fractional crevice spawners, deposited eggs in laboratory aquaria in the spaces created between stacks of ceramic tiles. Captively produced spotfin chubs were used as part of a larger stream restoration and fish reintroduction project in the Great Smoky Mountains National Park. The bloodfin darter, Etheostoma sanguifluum, was first used as a surrogate to develop techniques for spawning a closely related species, the endangered boulder darter, E. wapiti. Both darter species mated in a wedge created between two ceramic tiles. Our efforts have had variable but generally high success, with survival rates of 50–90% of eggs deposited. Captive production of nongame fishes can aid recovery of rare species or populations, aid in watershed restoration, and can help to refine water quality standards. In addition, captive breeding allows discovery of important behavioral or life history characteristics that may constrain reproduction of rare species in altered natural habitats.
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There is an increasing demand for aging data to provide inputs to stock assessment models for management of exploited fish populations. Image analysis software and computer hardware allow more rapid processing of samples and data. This paper describes a fully integrated system that has been in operation for 5 years and has been used to provide age estimates for more than 150 species. The system combines the requirements of high-quality “production” aging with the benefits of a customized image analysis system. The system improves the work environment, increases efficiency, aids data collection, and improves quality control. All aging studies require unbiased and precise age estimates; however, the ongoing process of production aging has particular requirements for quality assurance. A classification of aging studies is proposed based on objectives of the study, and the features and key procedural requirements of each study type are described.
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Many species of fish produced in aquaculture or for the ornamental fish trade exhibit sexual dimorphism in growth, age at maturity, secondary sexual characters, or other traits of interest. This has led to a desire to produce populations of only one sex for commercial ongrowing. Although direct sex reversal via manipulation of sex differentiation is used commercially (e.g., in tilapia aquaculture), in most cases there is a need to understand the sex determination system to some extent and manipulate this to produce monosex fish. Sex determination is the genetic or environmental process that establishes the sex (gender) of an organism, whereas sex differentiation is the process by which an undifferentiated gonad is transformed into an ovary or a testis. Fish are the most diverse group of vertebrates in terms of sex determination, and the number of fish species of interest to aquaculture keeps increasing. Together, these aspects explain the growing interest to understand how sex determination and differentiation produce the sex ratio. This review concentrates on recent research using the tools of molecular biology to broaden our understanding of the different aspects related to fish sex determination, both in model fish species and in species of commercial importance.
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We used radiotelemetry and mark-recapture tagging to determine the spatial movements of adults and juveniles (>180 mm total length) of a federally endangered, native Percichthyid fish, the trout cod Maccullochella macquariensis, in the Murray River, south-eastern Australia, to assist in its management and conservation. Trout cod exhibited strong evidence for site fidelity and homing in this study, typically utilizing only a few locations in the river channel and undertaking limited movements. The home range estimate for radiotracked fish was 61 ± 46 m (95% confidence interval). Movements of 1200 ± 46 m (95% confidence interval) were recorded for mark-recapture fish over longer time frames. No movements were recorded for 50% of fish. Larger movements (>3 km) were observed in <10% of individuals. While increased movement occurred with high flows during October and November in 1993, there was no evidence of an obligatory migration for this species. Several fish moved from the main river channel into floodplain channels and onto the nearby floodplain. No increase in movement was observed with season or with higher flows that occurred in July and August 1995. Conservation strategies for the species include the restoration of physical habitats. These results suggest that proximity to source populations may be influential in determining the likely timeframe necessary for recolonisation of restored habitats. Cite this article as: Koehn JD, Nicol SJ, McKenzie JA, Lieschke JA, Lyon JP, Pomorin K (2008) Spatial ecology of an endangered native Australian Percichthyid fish, the trout cod Maccullochella macquariensis. Endang Species Res 4:219-225 Export citation: Endnote - Reference Manager Mail this link - Contents Mailing Lists - RSS - Tweet - lang: en_US
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The present study quantitatively describes a significant stock of carp (Cyprinus carpio L.), an exotic pest species, in a temperate riverine floodplain wetland. Intensity and duration of flooding influenced relative abundance, distribution and recruitment. Average growth (mm) in length was described with the von Bertalanffy growth model for males (L∞ = 489, k = 0.249, t0 = -0.519), and females (L∞ = 594, k = 0.177, t0 = -0.609) to age 28. Variation in growth was described with a lognormal distribution of k. Total mortality (Z year-1) was 0.268-0.407 for males, 0.311-0.422 for females, 3.24 for age-0 juveniles and 1.80 for age-1 juveniles. Natural mortality (M year-1) was 0.199 for males and 0.262 for females. Fishing mortality (F year-1) was <0.05 for males and 0.11-0.30 for females. Gonadal changes indicated extended spawning seasons peaking in September 1999 and October 2000. Median sizes and ages at initial maturation were 307 mm, 584 g and 1.1 years for males and 328 mm, 688 g and 2.7 years for females. Sex ratio varied significantly with age from equal as juveniles to a significant male-bias as adults. This description will enable better stock assessment and development of simulations that evaluate potential pest management strategies.
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As part of an ongoing program of management for a critically endangered fish, we explored adaptive management as a method to overcome pervasive uncertainty regarding the reintroduction of trout cod (Maccullochella macquariensis Cuvier). We simulated the entire adaptive management cycle to explore the suitability of the approach for guiding threatened species management and to identify problems and barriers to "learning by doing". During the planning phase, a number of compromises were identified between specification of goals and objectives, the available management options, and current monitoring capacity. Undertaking a simulation of the implementation of alternate adaptive approaches to this reintroduction provided a number of insights into adaptive management in general. First, identifying the weak link in the process of inference emphasized the need to consider whether goals and objectives are achievable and meaningful and whether they complement monitoring and (or) any other limitations of the system. Second, in natural resource management, it is crucial to negotiate objectives in the light of what one can measure. Third, although there are lessons to be learned from each stage of the adaptive management cycle, there is value in simulating the entire adaptive management cycle, including management actions, monitoring, and the states of the system that lead to management intervention.
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The razorback sucker Xyrauchen texanus was historically widespread and abundant throughout the larger streams of the Colorado River basin, ranging from Sonora, Mexico, to Wyoming. The species was federally listed as endangered in 1991 because it has been extirpated from most of its range. Its decline is attributed to habitat loss and predation by nonnative fishes. Thirty years of federal and state effort have resulted in stocking millions of razorback suckers to the lower Colorado River basin, but only a few individuals have been recaptured because the young are rapidly consumed by introduced predators, resulting in insufficient recruitment to adulthood. Elderly, wild adults of this long-lived species are vanishing, and lower Colorado River basin recovery efforts now focus on replacement of these fish with repatriated (or reintroduced) adults. Stocking success and subsequent survival increases with size at release. When estimates of size-based, first-year survival rates were applied to individual batches of repatriated fish, we observed less than 1% overall first-year survival, and most fish stocked to date are thought to have been consumed soon after release. Overall, stocking has been unsuccessful, long-term survival is unknown, and no new populations have been established.
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Case histories of some of Australia's most threatened native freshwater fishes are presented. These include: six endangered species, Galaxias fontanus, G. johnsroni, G. pedderensis (Galaxiidae), Melanataenia euchamensis (Melanotaeniidae), Maccullochella sp. nov. and M. macquariensis (Percichthyidae): one vulnerable species, Galaxias tanycephalus: two potentially threatened species. Galaxias parvus and Prototroctes maraena (Prototroctidae); one indeterminate species. Maccllochella sp.; one restricted species, Macquaria australasica (Percichthyidae). Aspects of their taxonomy, distribution and reasons for their decline are discussed. Conservation management strategies that have been or are being applied to most of these species include protection of the fish and their habitats, establishment of refuge populations, and artificial propagation and re-establishment programmes.
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Trout cod (Maccullochella macquariensis, Cuvier) is a critically endangered species that now only occurs naturally in a 200 km reach of the Murray River in south-eastern Australia. An assessment of its habitat use was undertaken using radio telemetry to test the assumptions underlying conservation strategies for the species. Trout cod were more likely to be observed in deeper water associated with the low-flow channel. The importance of large wood habitat was dependent on its location within the river channel. In narrow river sections trout cod utilised location where large wood was abundant. In other locations, large wood was associated with deep scour pools that were utilised by trout cod. Our results support rehabilitation of large wood habitat in streams where this was a natural feature as part of the recovery program for this species.
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Ecology is a subject where theoretical predictions are often difficult to test experimentally in the field. To address this challenge, the Ecological Society of America suggested exploiting large-scale environmental management decisions in a scientific way. This 'adaptive management' constitutes one of the purposes of the Sustainable Biosphere Initiative. Meanwhile, in the current context of the biodiversity crisis, translocations and particularly reintroductions of threatened species are becoming more numerous. It is time for ecologists and wildlife managers to collaborate on these unique opportunities for large-scale studies.
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Radio-tracking was used in monitoring the reintroduction of on-grown 2 year-old trout cod Maccullochella macquariensis (Percichthyidae) (a nationally endangered freshwater fish) in both a large and small upland river. Thirty-six radio-tagged M. macquariensis were stocked into a site in each of the Murrumbidgee and Cotter Rivers (Australian Capital Territory). Restricted dispersal occurred in both rivers, with both samples of M. macquariensis remaining within 5 km of the release site for the duration of the study. Mortality was rapid and 1 month after release 61 and 31% of the sample was alive in the Murrumbidgee and Cotter Rivers, respectively. In the Murrumbidgee River, complete mortality had occurred 6 months after release. An individual survived in the Cotter River until 7 months after release. Predation by cormorants Phalacrocorax spp. and predation or scavenging by the common water rat Hydromys chrysogaster were the probable causes of mortality. Predator-assisted movement of radio-tags by cormorants occurred in both groups and had the potential to confound interpretation of active dispersal movements. Yes Yes
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Despite increasingly large investments, the potential ecological effects of river restoration programs are still small compared to the degree of human alterations to physical and ecological function. Thus, it is rarely possible to "restore" pre-disturbance conditions; rather restoration programs (even large, well-funded ones) will nearly always involve multiple small projects, each of which can make some modest change to selected ecosystem processes and habitats. At present, such projects are typically selected based on their attributes as individual projects (e.g., consistency with programmatic goals of the funders, scientific soundness, and acceptance by local communities), and ease of implementation. Projects are rarely prioritized (at least explicitly) based on how they will cumulatively affect ecosystem function over coming decades. Such projections require an understanding of the form of the restoration response curve, or at least that we assume some plausible relations and estimate cumulative effects based thereon. Drawing on our experience with the CALFED Bay-Delta Ecosystem Restoration Program in California, we consider potential cumulative system-wide benefits of a restoration activity extensively implemented in the region: isolating/filling abandoned floodplain gravel pits captured by rivers to reduce predation of outmigrating juvenile salmon by exotic warmwater species inhabiting the pits. We present a simple spreadsheet model to show how different assumptions about gravel pit bathymetry and predator behavior would affect the cumulative benefits of multiple pit-filling and isolation projects, and how these insights could help managers prioritize which pits to fill.
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Murray cod have undergone only a marginal reduction in their natural geographical range, but have declined markedly in abundance; trout cod have declined dramatically both in distribution and abundance. Translocations to outside the natural geographical range of Murray cod, particularly in the Wimmera and West Wimmera regions, have expanded the range of this species. However, as in the Murray-Darling system, the stocks in these areas have also declined. Trout cod are now considered endangered and Murray cod vulnerable. Any attempts to rectify this situation must include a stocking programme using hatchery-bred fish, together with active habitat management in selected areas.-from Authors
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Stocking wild fish populations with hatchery-bred fish has numerous genetic implications for fish species worldwide. In the present study, 16 microsatellite loci were used to determine the genetic effects of nearly three decades of Murray cod (Maccullochella peelii peelii) stocking in five river catchments in southern Australia. Genetic parameters taken from scale samples collected from 1949 to 1954 before the commencement of stocking were compared with samples collected 16 to 28 years after stocking commenced, and with samples from a local hatchery that supplements these catchments. Given that the five catchments are highly connected and adult Murray cod undertake moderate migrations, we predicted that there would be minimal population structuring of historical samples, whereas contemporary samples may have diverged slightly and lost genetic diversity as a result of stocking. A Bayesian Structure analysis indicated genetic homogeneity among the catchments both pre- and post-stocking, indicating that stocking has not measurably impacted genetic structure, although allele frequencies in one catchment changed slightly over this period. Current genetic diversity was moderately high (HE¼0.693) and had not changed over the period of stocking. Broodfish had a similar level of genetic diversity to the wild populations, and effective population size had not changed substantially between the two time periods. Our results may bode well for stocking programs of species that are undertaken without knowledge of natural genetic structure, when river connectivity is high, fish are moderately migratory and broodfish are sourced locally
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The gonadal development of Murray cod, Maccullochella peelii peelii, in Lake Charlegrark, Victoria, and adjacent farm ponds was evaluated. Gonadosomatic index, macroscopic classification and histological analysis were used to determine the age at first maturity and the gonadal development in this introduced population. There is a marked difference between the sexes in the size at first maturity, with females maturing at approximately 6 years of age and 2000 g in weight and males maturing at 3-4 years and 700 g. Gonadosomatic index data indicate that spawning occurs around November. Ovarian development in this species follows a pattern similar to that in a number of other teleosts. Testes have a lobular structure. Macroscopic evaluation of ovaries provided a good indication of the stage of the development of the gonad. However, the presence of spermatozoa throughout the year in the gonads of mature male fish makes the macroscopic evaluation of testicular development less reliable. Three cod, approximately 1% of the population, contained gonads with both ovarian and testicular tissue.
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Maccullochella macquariensis is a rare freshwater percichthyid fish that was formerly found in many localities throughout the Murray-Darling River system of eastern Australia. It is now restricted to two isolated habitats in Victoria. This paper gives an account of the species and its distribution, catalogues the known museum specimens, and provides photographs of representative individuals.
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The papers resulting from this symposium review the ecological and genetic effects of fish introductions throughout the world. Purposeful introductions rarely have achieved their objectives. Moreover, both intentional and unintentional introductions usually have been harmful to native fishes and other taxa through predation, competition, hybridization, and the introduction of diseases. We must learn from the past in order to avoid mistakes in the future. Introductions should not be used as a management tool without sufficient prior information and understanding to predict their effects. Introductions are often made or permitted because of the demands of certain interests groups (e.g., anglers or aquaculturists). Education of the public to the potential dangers and costs of such introductions is essential. Cooperation among management agencies is necessary to regulate and control both the purposeful and accidental introductions of fishes.
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Aims Australia is among one of the world’s wealthiest nations; yet, its relatively small human population (22.5 million) has been responsible for extensive deforestation and forest degradation since European settlement in the late 18th century. Despite most (∼75%) of Australia’s 7.6 million-km2 area being covered in inhospitable deserts or arid lands generally unsuitable to forest growth, the coastal periphery has witnessed a rapid decline in forest cover and quality, especially over the last 60 years. Here I document the rates of forest loss and degradation in Australia based on a thorough review of existing literature and unpublished data. Important Findings Overall, Australia has lost nearly 40% of its forests, but much of the remaining native vegetation is highly fragmented. As European colonists expanded in the late 18th and the early 19th centuries, deforestation occurred mainly on the most fertile soils nearest to the coast. In the 1950s, southwestern Western Australia was largely cleared for wheat production, subsequently leading to its designation as a Global Biodiversity Hotspot given its high number of endemic plant species and rapid clearing rates. Since the 1970s, the greatest rates of forest clearance have been in southeastern Queensland and northern New South Wales, although Victoria is the most cleared state. Today, degradation is occurring in the largely forested tropical north due to rapidly expanding invasive weed species and altered fire regimes. Without clear policies to regenerate degraded forests and protect existing tracts at a massive scale, Australia stands to lose a large proportion of its remaining endemic biodiversity. The most important implications of the degree to which Australian forests have disappeared or been degraded are that management must emphasize the maintenance of existing primary forest patches, as well as focus on the regeneration of matrix areas between fragments to increase native habitat area, connectivity and ecosystem functions.
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Some species typically used in stock enhancement in Japan were reviewed, and the causes of program success or failure were analyzed in an attempt to determine the best approach for future stocking. Recent successes in salmon stock enhancement are attributed to improvement of the return rate resulting from physiological and behavioral research. In scallop stock enhancement, high quality of seedlings, improvement of the environment, crop rotation, and the marketing system have supported a steady yearly increase in yield. Flounder stock enhancement in Fukushima Prefecture has achieved a 30% recapture rate, and the cost-benefit ratio is estimated to be more than 300%. In the case of red sea bream, because recreational anglers now catch a higher percentage of stocked fish than do commercial fishermen, a new method of fisheries regulation may be required, as recreational anglers now pay only little of the costs of the stocking program. Masu salmon and abalone stocks are best preserved by the protection of spawning grounds. In marine ranching of striped jack, understanding of behavioral ecology seems to be essential for the success of this project and the prevention of genetic pollution. Behavioral quality of stocked fish is a determining factor in the success of stock enhancement, so attempts have been made to improve behavioral quality in several species. Although sea farming projects have been well supported by basic research on diet, physiology, morphology, and behavior, the present authors believe that ecological research in the natural habitat of each species is indispensable for the success of stock enhancement and that the national and prefectural governments should take the initiative in protection of genetic diversity.
Dear Sir, The frequent opportunities I have had of receiving pleasure from your writings and conversation, have induced me to prefer offering to the Royal Society through your medium, this Paper on Life Contingencies, which forms part of a continuation of my original paper on the same subject, published among the valuable papers of the Society, as by passing through your hands it may receive the advantage of your judgment.
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We have isolated 102 polymorphic microsatellite loci from an enriched Murray cod DNA library and also assessed their amplification success in 13 native and six introduced freshwater fish species. The loci will serve the dual purpose of assessing wild population genetic structure for future conservation efforts, and for identifying markers for key quantitative trait loci important for aquaculture.
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Atlantic cod have been a primary target for marine stock enhancement since the 1880s. In the early part of this period, hatched larvae were released in Norway, the USA and Canada. The last larval releases were conducted in Norway in 1971, and a century of cod larvae releases were halted without any clear evidence of benefit. Since the early 1980s, the focus has been on production of larger, more viable juvenile cod. Emphasis has been given to the design of tag–release programmes involving large-scale releases and ecosystem analysis in selected ecosystems. Most of this research has been carried out in Norway, where more than one million tagged juvenile cod have been released. Smaller stocking experiments have also been performed in Denmark, Sweden, the Faroe Islands and the USA. This paper reviews the major findings from these programmes. We include summaries and evaluations of rearing techniques for juvenile cod, methods of tagging and recapture, experimental fishing, migration, mortality and growth rates in the different habitats, genetic analysis, and ecosystem studies that have tried to describe the variation in the cod carrying capacity of selected release areas. Despite relatively large variation in environmental conditions, in cod production and in fishing mortality along the Norwegian coast, results indicate that, under the conditions experienced during the 1980s and 1990s, releases of juvenile cod did not significantly increase cod production and catches. The biological limitations and future prospects of Atlantic cod stock enhancement are addressed.
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Setting ecological goals for restoring fish communities in larger rivers is hampered by a lack of knowledge of the natural reference conditions. The lowland river Vecht has become highly regulated since 1850. Since the 1970s, measures have been taken to improve water quality followed by the construction of fishways along weirs in the 1990s to rehabilitate migration. We aim to assess the degree of deviation of the current fish community in the river from its pre-regulation state. The assessment is based on a comparison with the less impacted river Biebrza in Poland as a geographical reference, involving a semi-quantitative stepwise reconstruction based on available historic evidence. Electrofishing was used to describe the current quantitative species compositions of the fish communities in the rivers Vecht and Biebrza and historical records of the Vecht region were used to crosscheck the reconstructed fish community around 1850 after correcting for zoogeographical differences. Despite various rehabilitation measures, the deviation from the natural reference is still large. Currently, perch Perca fluviatilis and bream Abramis brama are much more abundant, and bleak Alburnus alburnus, white bream Blicca bjoerkna and most rheophilic species are far less abundant, than before. The main reasons for this deviation appears to be the present quality of the habitats and, for some species, the poor connectivity with the sea as well as with small tributaries. The approach used should be widely applicable to derive natural references, assess rehabilitation success or improve the ecological assessment of integrity as imposed by the European Water Framework Directive. Copyright © 2008 John Wiley & Sons, Ltd.
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Summary1. A key element of conservation planning is the extremely challenging task of estimating the likely effect of restoration actions on population status. To compare the relative benefits of typical habitat restoration actions on Pacific salmon (Oncorhynchus spp.), we modelled the response of an endangered Columbia River Chinook salmon (O. tshawytscha) population to changes in habitat characteristics either targeted for restoration or with the potential to be degraded.2. We applied a spatially explicit, multiple life stage, Beverton-Holt model to evaluate how a set of habitat variables with an empirical influence on spring-run Chinook salmon survivorship influenced fish population abundance, productivity, spatial structure and diversity. Using habitat condition scenarios – historical conditions and future conditions with restoration, no restoration, and degradation – we asked the following questions: (i) how is population status affected by alternative scenarios of habitat change, (ii) which individual habitat characteristics have the potential to substantially influence population status and (iii) which life stages have the largest impact on population status?3. The difference in population abundance and productivities resulting from changes in modelled habitat variables from the ‘historical’ to ‘current’ scenarios suggests that there is substantial potential for improving population status. Planned restoration actions directed toward modelled variables, however, produced only modest improvements.4. The model predicted that population status could be improved by additional restoration efforts directed toward further reductions in the percentage of fine sediments in the streambed, a factor that has a large influence on egg survival. Actions reducing fines were predicted to be especially effective outside the national forest that covers most of the basin. Scenarios that increased capacity by opening access to habitat in good condition also had a positive but smaller effect on spawner numbers.5. Degradation in habitat quality, particularly in percent fine sediments, within stream reaches located in the national forest had great potential to further reduce this population’s viability. This finding supports current forest planning efforts to minimise road density and clear-cut harvests and to return forest stand structure in dry regions to the historical condition that promoted frequent low-intensity fires rather than catastrophic stand-replacing fires, as these landscape factors have been shown to influence percent fine sediment in streams.6. Together, these results suggest that planning focusing on protecting currently good habitat, reducing fine sediments to promote egg survival and increasing spawner capacity will be beneficial to endangered spring-run Chinook population status.
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The world's fish species are under threat from habitat degradation and over-exploitation. In many instances, attempts to bolster stocks have been made by rearing fish in hatcheries and releasing them into the wild. Fisheries restocking programmes have primarily headed these attempts. However, a substantial number of endangered species recovery programmes also rely on the release of hatchery-reared individuals to ensure long-term population viability. Fisheries scientists have known about the behavioural deficits displayed by hatchery-reared fish and the resultant poor survival rates in the wild for over a century. Whilst there remain considerable gaps in our knowledge about the exact causes of post-release mortality, or their relative contributions, it is clear that significant improvements could be made by rethinking the ways in which hatchery fish are reared, prepared for release and eventually liberated. We emphasize that the focus of fisheries research must now shift from husbandry to improving post-release behavioural performance. In this paper we take a leaf out of the conservation biology literature, paying particular attention to the recent developments in reintroduction biology. Conservation reintroduction techniques including environmental enrichment, life-skills training, and soft release protocols are reviewed and we reflect on their application to fisheries restocking programmes. It emerges that many of the methods examined could be implemented by hatcheries with relative ease and could potentially provide large increases in the probability of survival of hatchery-reared fish. Several of the necessary measures need not be time-consuming or expensive and many could be applied at the hatchery level without any further experimentation.
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WinBUGS is a fully extensible modular framework for constructing and analysing Bayesian full probability models. Models may be specified either textually via the BUGS language or pictorially using a graphical interface called DoodleBUGS. WinBUGS processes the model specification and constructs an object-oriented representation of the model. The software offers a user-interface, based on dialogue boxes and menu commands, through which the model may then be analysed using Markov chain Monte Carlo techniques. In this paper we discuss how and why various modern computing concepts, such as object-orientation and run-time linking, feature in the software's design. We also discuss how the framework may be extended. It is possible to write specific applications that form an apparently seamless interface with WinBUGS for users with specialized requirements. It is also possible to interface with WinBUGS at a lower level by incorporating new object types that may be used by WinBUGS without knowledge of the modules in which they are implemented. Neither of these types of extension require access to, or even recompilation of, the WinBUGS source-code.
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A stochastic population model has been developed for exploring the conservation management of the endangered fish trout cod (Maccullochella macquariensis) in the circumstances of incomplete understanding of the ecology of the species as well as the absence of appropriate data for the estimation of some vital rates. The model includes a stage-structured approach with environmental and demographic variation, and examines three types of density dependence: Beverton–Holt, Ricker and a biomass approach that we have developed to incorporate intraspecific competition beyond recruitment to 1-year olds. The stochastic model was used to explore the current and future status of the protected and last self-sustaining natural population of trout cod, restricted to a 200 km section of the Murray River in south-eastern Australia, under the different density-dependent mechanisms. Current practices for reintroducing trout cod were also evaluated. The analysis indicates that the protected natural population may be stable provided that it remains free from any significant disturbance. However, the analysis also indicates that trout cod may be very sensitive to any reduction in adult survival and remain potentially vulnerable to continued anthropogenic disturbance, in particular fishing. The analysis also indicates that the current practice of releasing fingerlings to establish a reintroduced population was more likely to fail than releasing on-grown 1-year-old fish at reintroduction sites. Furthermore, the traditional density-dependent mechanisms have less support than the applied biomass approach. The stochastic population model developed becomes a resource for guiding the conservation management and further research into the ecology of trout cod.