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The commercial fishery for ocean leatherjackets (Nelusetta ayraudi, Monacanthidae) in New South Wales, Australia
Abstract
The ocean leatherjacket (Nelusetta ayraudi) has a long history of commercial exploitation in New South Wales, Australia. Records of reported landings indicate that substantial peaks of between 600 and 900 tonnes per annum occurred during the 1920s and again during the 1950s. These peaks were followed by large declines, which suggest that this species is vulnerable to over-exploitation. In recent years from 2000/01 to 2006/07, annual commercial landings of ocean leatherjackets using oceanic demersal fish traps and demersal otter trawl have increased from 134 to 430 tonnes. Between 2003 and 2005 ocean leatherjackets in commercial landings ranged approximately between 22 and 65 cm in total length. Ocean leatherjackets were fully recruited to the fishery at two years of age, with the majority of the catch (83%) aged either two or three years. The instantaneous total mortality rate was estimated from an age-based catch curve as 1.1. Natural mortality was estimated as approximately 0.5, based on a maximum age of 6 years. Yield per recruit indicated that under current levels of exploitation the yield per recruit would be maximized at a length at first harvest of 35 cm in total length.
... The monachanthid Nelusetta ayraud is a relatively understudied fish, however it supports substantial commercial and recreational fisheries. Distributed along the southern coast of Australia from Cape Moreton, Queensland, to North West Cape, Western Australia, N. ayraud are targeted by commercial trap and trawl fisheries (Klaer, 2001;Miller and Stewart, 2009) and recreational line fisheries (Murphy et al., 2020). The largest fishery occurs off New South Wales (NSW), with historical landings reported at up to 900 t per annum (Miller and Stewart, 2009;Smoothey et al., 2021). ...
... Distributed along the southern coast of Australia from Cape Moreton, Queensland, to North West Cape, Western Australia, N. ayraud are targeted by commercial trap and trawl fisheries (Klaer, 2001;Miller and Stewart, 2009) and recreational line fisheries (Murphy et al., 2020). The largest fishery occurs off New South Wales (NSW), with historical landings reported at up to 900 t per annum (Miller and Stewart, 2009;Smoothey et al., 2021). The fishery has exhibited substantial decadal-scale fluctuations in landings that may reflect vulnerability to overfishing or natural variation in population abundance (Klaer, 2004;Miller and Stewart, 2009;Smoothey et al., 2021). ...
... The largest fishery occurs off New South Wales (NSW), with historical landings reported at up to 900 t per annum (Miller and Stewart, 2009;Smoothey et al., 2021). The fishery has exhibited substantial decadal-scale fluctuations in landings that may reflect vulnerability to overfishing or natural variation in population abundance (Klaer, 2004;Miller and Stewart, 2009;Smoothey et al., 2021). ...
... opposite to the predictions of the TSR model), indicating that in this case the TSR model could be outweighed by variation associated with habitat and nutrition and not just temperature, as previously documented for many other species (Yamahira and Conover 2002;Floeter et al. 2005;Robertson et al. 2005;Lafferty 2007, 2012;Trip et al. 2014). More generally, our findings on age composition are consistent with those reported for other monacanthids in Miller and Stewart (2009) with the exception of the oldest fish recorded here. The maximum age recorded for M. scaber in this study was 19 years, which is much longer than the previous lifespan estimates of 5 years (Poynter 1980), and represents the greatest age reported for the family Monacanthidae to date. ...
... Although this finding highlights an important key demographic feature of this species, our results partially also support the hypothesis that M. scaber might undergo short vertical movements that could be associated with either spawning dynamics or feeding habits. Similar trends have been observed in many gonochoristic lutjanids (Guerra Campos and Bashirullah 1975;Reshetnikov and Claro 1976;Grimes and Huntsman 1980;Grimes 1987;Everson et al. 1989) and in the ocean leatherjacket Nelusetta ayraudi (Lindholm 1984;Miller and Stewart 2009), although actual movement patterns have not been observed. Alternatively, this pattern reflects a possibility that males are more susceptible to trawling. ...
Demography and life-history characteristics of reef fishes may vary as a consequence of ecological and environmental factors that lead to changes among populations. We evaluated variation in life-history traits in the leatherjacket Meuschenia scaber (Monacanthidae) through age-based analysis of 2112 fish collected from three locations in New Zealand distributed along an 8° latitudinal and 5 °C SST gradients. Meuschenia scaber showed distinct differences in age structure, growth patterns, maximum size and age, sex ratio and mortality across this latitudinal gradient. At warmer lower latitudes (Hauraki Gulf) the population displayed significantly greater mean adult body size (Lmax) and asymptotic length (L∞) in comparison with the other two locations. Fish from Tasman Bay (mid-range latitude) had a longer life span (Tmax) and a maximum age of 19 years, which represents the longest-lived monacanthid documented to date. Fish from Pegasus Bay (cooler higher latitude) showed a slower initial growth than lower latitude counterparts. The difference in maximum age between the sexes declined clinally from 7 years in the Hauraki Gulf to 3 years in Tasman Bay and 1 year in Pegasus Bay. Meuschenia scaber females tended to display heavier and larger body size than males at all three locations. Sex ratios varied among populations and with depth, suggesting females in the Hauraki Gulf and Tasman Bay may move into deeper water with age. Given the increasing global exploitation of monacanthids in multispecies fisheries and their long-living nature, our results provide valuable age-based demographic information essential for future conservation, monitoring and management programs.
... Historical catch data indicate substantial variations in ocean jacket abundance off south-eastern Australia in the 1920s and 1950s (Miller & Stewart 2009). Ocean jacket is a relatively short-lived species (six years), reaching maturity within two to three years and exhibiting large cyclical changes in abundance (Miller & Stewart 2009). ...
... Historical catch data indicate substantial variations in ocean jacket abundance off south-eastern Australia in the 1920s and 1950s (Miller & Stewart 2009). Ocean jacket is a relatively short-lived species (six years), reaching maturity within two to three years and exhibiting large cyclical changes in abundance (Miller & Stewart 2009). As a byproduct species, ocean jacket has not been the subject of formal stock assessments. ...
... In addition, another kyphosid, luderick, Girella tricuspidata, is an important component of the commercial inshore/estuarine gillnet fishery and the recreational line fishery in south-eastern Australia with a combined annual catch of 700-1000 t(Henry & Lyle, 2003;Rowling et al., 2010). Likewise, Kyphosus species are retained in the commercial fisheries in the south-eastern Gulf of California, where catches have increased since the collection of fishery records started in the 1990s(Erisman et al., 2010;Rojo-Vázquez et al., 2001) and Chinaman leatherjacket, Nelusetta ayraud, was typically discarded but is now targeted by commercial trap fishers in south-eastern Australia and is also retained by the Great Australian Bight Trawl Fishery(Miller & Stewart, 2009;Moore et al. 2020).Due to its vast coastline (c. 12,800 km) and the large number of teleosts captured by numerous fisheries, WA is divided into four coastal bioregions, within which teleosts are grouped into five ecological suites(Department of Fisheries, 2011;Newman et al., 2018). ...
Quantifying discards is essential for assessing the impact of fisheries on non‐target species and the ecosystems in which these fisheries operate. In Western Australia (WA), fishers are required only to report catches of retained species. For the currently operating shark fisheries of WA, the authors quantified catch time series of discarded teleosts using data from at‐sea observers collected since 1993. Sixty‐two teleost species were observed in the catch of which 20 were routinely discarded. The most commonly discarded teleosts were western buffalo bream/silver drummer, Kyphosus cornelii/K. sydneyanus, and dusky morwong, Dactylophora nigricans. Annual discards peaked in the 1990s; nonetheless, current discard levels, 36.9 ± 2.1 (s.e.) t year⁻¹, are much lower than the overall annual retained catches (c. 1000 t year⁻¹). The catch time series reconstructed in this study are important inputs for assessing the ecosystem‐based approach used for managing WA's shark fisheries.
... Our positive results could potentially lead to further investigations into monitoring fishery landings of species that are processed at sea, and consequently have been viewed as requiring relatively expensive onboard monitoring (via trained scientific observers). Candidate species include Monacanthids and elasmobranchs that are beheaded at sea (Miller and Stewart, 2009;Braccini et al., 2006;Huveneers et al., 2007). ...
The COVID-19 global pandemic-related restrictions during 2020 severely impacted the Australian seafood industry, including essential scientific monitoring to support stock assessment and to demonstrate sustainability. Here we detail a novel, collaborative monitoring program between scientists and the seafood industry to generate length and age compositions that were representative of one of the largest, most valuable, and controversial fisheries along eastern Australia, the pre-spawning ocean run fishery for Sea Mullet Mugil cephalus that is predominantly a roe fishery. The standard approach to monitoring this fishery has been to base trained scientific staff at the major processing facility for M. cephalus, where they access whole fish from entire catches to generate representative length and age compositions during the peak season, April to May. Covid-19 restrictions prevented this approach for 2020 in eastern Australia. In recognition that in addition to the high-value roe, all components of the female fish are utilized (heads and guts for bait, bodies for human consumption), a multi-stage, spatially stratified sampling design was investigated. Female heads were retained from randomly selected catches from each of the three major fishing zones and transported to the New South Wales Department of Primary Industries fish laboratory based in Sydney. Head lengths (HLs) were measured and converted to Fork Lengths (FLs) using a HL to FL relationship. The resulting fish length compositions from each catch were subsequently combined based on: (i) relative catch size of females within an ocean zone, and; (ii) the relative reported landings of females in each ocean fishing zone. Otoliths were randomly collected from heads sampled from each ocean zone and used to estimate age. The resulting ocean zone to age matrix was combined with the relative reported landings of female fish in each ocean fishing zone to generate a total female age composition for the fishery. The estimated age composition of females were typical in being mainly between ages 3 and 6, with a strong presence of 4-year olds. This stronger cohort was present as 3-year olds in 2018/19 and 5-year olds in 2020/21, thus providing confidence that our sampling was representative of the fishery. The study reinforces the positive outcomes that can be generated through co-management between scientists and the seafood industry.
... Fish trap has been reported to be the principal fishing device throughout the Bahamian and Caribbean islands as it was found to be an efficient device for capturing fishes in areas where coral formation prevents the use of trawls and other nets (Munro, 1974). In New South Wales of Australia, the majority of ocean leather jackets were fished using demersal fish traps (Miller and Stewart, 2009). Development of collapsible trap fishing technique is of recent origin. ...
The efficiency of four different funnel designs viz., rectangular, oval, heart-in and circular shaped funnels were tested in a serial collapsible fish trap through fishing trials conducted in a coastal fishing ground off Mandapam in Tamil Nadu, south-west coast of India. A total of 24 fishing operations were carried out. Significant difference in overall catch rate of experimental trap with respect to funnel designs could be observed (p<0.05). Among four types of funnels tested with the constant rear end funnel perimeter of 560 mm, traps with oval funnel caught more number of fishes (121 nos. in 24 soaking days) than those fitted with rectangular, heart-in shaped and circular type of funnels with 37; 82 and 70 nos. in 24 soaking days respectively. The study revealed that oval shaped funnel was superior to the other funnel designs with 560 mm circumference.
... a Equivalent to 668 g m −2 seafloor, or 606 g m −2 reef surface area b Equivalent to 384 g m −2 seafloor year −1 , or 302 g m −3 reef year −1 c M reduced to match Z = 0.6(Stewart et al. 2001) d M reduced to match Z = 1.1(Miller and Stewart 2009) e M reduced to match Z = 0.32(Stewart and Hughes 2009) ...
It was recently demonstrated that oil platforms are among the most productive marine fish habitats (Claisse et al. in Proc Natl Acad Sci USA 111:15462–15467, 2014). Designed artificial reef systems are similar, albeit smaller, modified habitats designed to accommodate fish assemblages. We compared fish production at a large designed reef to reported production at oil platforms. Given the focus in artificial reef research on distinguishing between new and aggregated fish production, we used a different approach to that of Claisse et al. (Proc Natl Acad Sci USA 111:15462–15467, 2014) to calculate production, based on a steady-state assumption. This assumption simplifies the analysis and distinguishes ‘local production’, ‘new production’, and ‘biomass flux’. Comparing biomass flux with standing stock biomass enables a new approach to address the production versus attraction debate, by revealing how much biomass is exposed to fishing compared to how much has local production. The local fish production at this artificial reef was 384 g m−2 year−1, which is within the 105–887 g m−2 year−1 range reported by Claisse et al., although our study included visitor species not included by Claisse et al. We estimate that the fish production new to the ecosystem may only be 4–5 % of the local production, due to the large abundance of visitor species on this reef. The annual flux of biomass across this reef was very large, ~380 times greater than the standing stock biomass, meaning that this reef is vulnerable to overexploitation from fishing. Our results show that like oil platforms, designed artificial reefs can be very productive marine habitats, but may not greatly increase the net fish production in a system. The method detailed here will allow similar studies to be done relatively simply at other marine habitats, including fish aggregation devices.
... In group spawners, where large amounts of sperm are advantageous to the chances of males successfully fertilizing eggs, males have gonads of equivalent sizes to females. In contrast, characteristics of being promiscuous and polygynous include their relatively high fecundity, similar growth rates and longevity between sexes (Miller et al. 2010), similar sizes and ages at sexual maturity between sexes and the proposed formation of large spawning aggregations in offshore waters (Miller 2007). It should be noted that the formation of large spawning aggregations has not been directly observed due to the depths at which they are thought to occur, rather inferred from depth soundings of schools of fish and the capture of running ripe fish from those schools. ...
The ocean leatherjacket (Nelusetta ayraudi) is one of the largest members of the family Monacanthidae. Distributed throughout inshore waters around the southern half of Australia, this schooling species supports substantial commercial and recreational fisheries. N. ayraudi do not conform to either of the general reproductive modes reported within the family, but exhibit characteristics of both strong social reproductive behaviour and of being promiscuous and polygynous. Sexual dimorphism, with males and females exhibiting differing colouration and body shapes, and ripe ovaries being an order of magnitude larger than ripe testes, are characteristic of social reproductive behaviour and pair spawning. In contrast, high batch fecundity (mean of 320 oocytes per gram of body weight), similar sizes and ages at sexual maturity (350 mm and 2.5 years respectively) and the formation of large spawning aggregations in offshore waters are characteristic of being promiscuous and polygynous. Similar to many other coastal marine species off the east and west coasts of Australia, N. ayraudi are partial spawners during the austral winter months with spawning restricted to the part of their distribution that is towards the upper area of the prevailing currents. It is hypothesized that N. ayraudi off eastern Australia have evolved a life-history strategy whereby fish move northwards through time, spawning occurs in these more northern waters and the southerly flowing Eastern Australian Current facilitates dispersal of eggs and larvae southwards. The reproductive characteristics described provide various options to fishery managers who wish to enhance the sustainability of the fishery through increased egg production. These include spatial and temporal fishing closures to protect breeding fish during the spawning period, the protection of juveniles through either inshore area closures, improving the selectivity of fishing gears and/or regulated minimum legal lengths.
... Thought to be endemic to Australian waters, N. ayraudi are distributed from North West Cape in Western Australia around the south of the continent to Cape Morton in Queensland (Kailola et al. 1993). In New South Wales (NSW) waters, annual commercial landings of N. ayraudi have increased rapidly from 134 to 430 tonnes between 2000-2001-2007(Miller and Stewart 2009). Despite the rapidly expanding commercial fishery, there exists almost no information on the biology of N. ayraudi on which to base the management of this species. ...
Nelusetta ayraudi (the ocean leatherjacket) is an endemic Australian monacanthid species distributed from North West Cape (Western Australia) south to southern Queensland. The commercial and recreational fisheries targeting Nelusetta ayraudi have expanded substantially along the coast of New South Wales (NSW) in recent years but there exists little biological information on which to base effective management of this growing fishery. World-wide, only a few studies have aged monacanthids. Of these, researchers have interpreted periodic increments in bony structures such as vertebrae and anterior dorsal spines in preference to those found in otoliths. In this study we estimated age of N. ayraudi by counting growth increments in sectioned otoliths. The periodicity of increment formation was validated using a vital stain, (oxy-tetracycline), injected into young-of-the-year fish. Growth was rapid especially as juveniles with N. ayraudi attaining approximately 220 mm after 1 year and 340 mm after 2 years. No differences in growth rates were detected between sexes or between fish captured at different latitudes (zones). The largest male (605 mm, Total Length—TL) and female (656 mm, TL) were both recorded from northern NSW, with both sexes attaining the maximum age of 6+ years from northern and southern NSW. The von Bertalanffy parameters describing growth for N. ayraudi were = 591 mm (TL), k = 0.377 year−1 and t
o = −0.247 years.
The effectiveness of four different funnels such as Rectangular, Oval, heartin and Circular shaped funnels were tested in a serial collapsible fish trap through fishing trials conducted in a coastal fishing ground of Mandapam of Tamil Nadu, India. A total of 24 fishing operations were carried out. The significant difference in the overall catch rate of the experimental trap with respect to funnels could be observed (P<0.05). Among four types of funnels tested with the constant rear end funnel perimeter of 700 mm, traps with Oval funnel caught high number of fishes (89 No’s/24 soaking days) than those fitted with Rectangular, Heart-in shaped and Circular type of funnels with 34 No’s/24 soaking days, 37 No’s/24 soaking days and 15 No’s/24 soaking days respectively. The study revealed that Oval shaped funnel was superior to the other shapes of funnels with 700 mm circumference.
The age and growth of filefish, Thamnaconus modestus (Günther 1877) in the southern waters of Korea were investigated. Samples were collected with commercial trawl catches during the period from May 2009 to December 2011. Of the 2,626 specimens collected, the sex ratio was not significantly different from 1:1 (P > 0.05). The total length ranged from 11.3 to 42.1 cm. The gonadosomatic index for both sexes was the highest in May to June, indicating that May to June is the main spawning period. The length of females at sexual maturity was 25.92 cm. The length-weight relationship of the filefish was TW = 0.0121TL3.0536 (n = 1,692, r2 = 0.9034, P < 0.001). The age of the sampled individuals was estimated by counting growth rings recorded on the 5th vertebrae; ages ranged from 0 to 9 years. The filefish of the same age displayed a high individual variation in total length. Length-at-age data were fitted by using the Von Bertalanffy growth model. The estimated Von Bertalanffy growth parameters were L∞ = 42.04 cm, k = 0.21 year−1 and t0 = −1.56 for females, L∞ = 41.20 cm, k = 0.18 year−1 and t0 = −2.36 for males, and L∞ = 43.16 cm, k = 0.17 year−1 and t0 = −2.18 for the combination of both male and female. These data can be used as useful biological information for the future fishery management of filefish resources in Korean waters.
Haul-by-haul steam trawler catch and effort data for 1918–23, 1937–43 and 1952–57, which cover a large portion of the history of steam trawling in the Australian South East Fishery, were examined in detail for the
first time. There were 64371 haul records in total. The catch-rate for all retained catch combined shows a strong decline overall, with a brief recovery during World War II, probably due to increased retention of previously discarded species. The fishing fleet moved to more distant fishing grounds and deeper waters as the catch-rate declined. The catch-rates of the main commercial species followed a similar pattern in a number of regions within the fishery. The catch-rate of the primary target species – tiger flathead (
Neoplatycephalus richardsoni) – dropped considerably from the early, very high, catch-rates. Chinaman leatherjacket (Nelusetta ayraudi) and latchet (Pterygotrigla polyommata) – species that were apparently abundant in the early years of the fishery, virtually disappeared from catches in later years. The appearance of greater catches of jackass morwong (Nemadactylus macropterus), redfish (Centroberyx affinis) and shark/skate during the war and afterwards was probably due to increased retention of catches of these species. The disappearance of certain species from the catch may be due to high fishing pressure alone, or to a combination of fishing pressure, changes in the shelf habitat possibly caused by the trawl gear, and environmental fluctuations.
This field guide covers the major resource groups likely to be encountered in the fisheries of Kuwait, Eastern Saudi Arabia, Bahrain, Qatar, and the United Arab Emirates. It includes marine plants, shrimps, lobsters, crabs, bivalves, gastropods, cephalopods, sharks, batoid fishes, bony fishes, sea snakes, sea turtles, sea birds, and marine mammals. In order to serve as a tool for ecological and biodiversity studies, all species know from the Gulf of certain groups are included. These include the sharks, batoid fishes, bony fishes, sea turtles, and marine mammals. Each resource group is introduced by a general section on technical terms and measurements pertinent to that group and an illustrated guide to higher taxonomic groups when relevant. Species are then treated in a subsequent guide that includes scientific nomenclature, common English and Arabic names where available, size information, information on habitat, biology, and fisheries, diagnostic features, and one or more illustrations, some of which are included in colour. The guide is fully indexed and a list of references is appended.
Observers onboard commercial trap vessels quantified the sizes of fish in the discarded and retained catch for the major species in the New South Wales (NSW) demersal trap fishery. Selectivity ogives were calculated for the two mesh types used in the fishery, 50mm hexagonal wire mesh and 50mm×75mm welded mesh, by comparing the sizes of fish retained in traps with these meshes with the sizes of fish retained in control traps of 37mm hexagonal wire mesh. The selectivity of 50mm hexagonal wire was inappropriate for all important species with minimum legal size limits in the fishery, with large proportions of catches being undersized fish which were subsequently discarded with unknown mortality. Traps with back panels of 50mm×75mm welded mesh significantly reduced the catch of undersized fish, but also reduced the catches of important species without minimum legal size limits. Mesh selectivity was a direct function of fish body depth and the maximum aperture of the trap mesh on the back panel of fish traps.
The total annual fecundity of mackerel, Scomber scombrus L., during a spawning season is produced by release of discrete batches of eggs. Total fecundity is then the product of the number of batches times the batch fecundity (Fbw). An extensive trawl survey of the Western mackerel stock in the NE Atlantic was undertaken in the 1989 spawning season. Batch fecundity was estimated for 298 fish by counting hydrated eggs in ovaries just prior to ovulation. Fbw, expressed as eggs g−1 body weight, varied with latitude: south of 51°N, Fbw= 55.49, s.e.= 2.04, n= 227; between 51°N and 55°N, Fbw= 45.72, s.e.= 3.41, n= 52 and north of 55° N, Fbw= 41.33, s.e.= 5.52, n= 19. It is suggested that as spawning fish migrate northwards the batch size decreases with progress of the spawning season.
Bottom trawl surveys were conducted in the southwest monsoon season in 1996 (survey 1) and in the northeast monsoon season in 1996-97 (survey 2) throughout Vietnamese waters. The surveys mainly covered the depth zone 50-200 m but in the northeast monsoon season the depth zone 20-50 m was included in the northern and southern areas. Overall, 273 trawl hauls were conducted. The total biomass for Vietnamese waters in the depth zone 20-200 m was estimated at 700 000 t . Biomass estimates are given for the most abundant species. A relatively higher mean catch-per-unit effort (CPUE) was obtained from survey 2 than from survey 1 and in partcular at depth ranges 50-100 and 100-200 m in south Vietnam. Overall, the dominant families were Monacanthidae (34%), Carangidae (15%), Trichiuridae (9%) and Synodontidae (6%).
The growth of the planedhead filefish Stephanolepis hispidus was studied on individuals sampled from a small-scale fishery off Gran Canaria (Canary Islands, central-east Atlantic) between March 1998 and August 1999. The age of the sampled individuals, which ranged from 0 to 3 years, was estimated using both the length frequency distribution and the count of growth rings recorded on the anterior dorsal spine. The mean total length of the 0 age class was 10.9 cm, while the ages classes 1, 2 and 3 showed a mean length of 15.8, 19.4 and 21.4 cm, respectively. Differences in the growth rhythms were observed between the sexes. The asymptotic lengths (L ∞) were 25.7 and 27.4 cm for females and males, respectively. The curvature parameter (K) of the von Bertalanffy growth equation was 0.40 per year. The amplitude of the seasonal growth oscillation of the von Bertalanffy growth equation (C = 0.15) and the Winter Point (WP = 0.19) indicate a seasonality in the growth pattern, being slowest at the end of the winter.
Ocean leatherjackets (Nelusetta ayraudi) are distributed along the entire coast of New South Wales (NSW) contributing significantly to the total catch of fish taken from the NSW Ocean Trap and Line Fishery (~340 tonnes in 2005/2006), in addition to other NSW fisheries, such as the Ocean Fish, Ocean Prawn and Haul-net Fisheries. In spite of their significance in commercial fisheries world-wide, only few studies have aged monacanthids. Of those, researchers have mainly used bony structures, such as vertebrae and anterior dorsal spines. In this study, commercially captured ocean leatherjackets were aged by counting growth increments in thin-sectioned otoliths. The periodicity of increment formation was validated using a vital stain oxy-tetracycline (OTC) injected into young of the year fish (0+). The von Bertalanffy growth function parameters provided good estimates of growth, k = 0.163 yr-1, t0 = -0.565 yrs and L∞ = 886 mm. The fishery was found to be dominated by two and three year old fish making up 83% of the ocean leatherjackets captured. The oldest fish (5+) and largest fish from both sexes (male - 605 mm, female - 656 mm) were found in northern NSW. All fish displayed a rapid rate of growth especially as juveniles, with no significant differences in growth between sexes and locations (southern and northern NSW). Ocean leatherjackets showed a geographical and temporal 'preference' for spawning. Gonado-somatic indices (GSI) revealed a peak in spawning during August in northern NSW. During this period adult fish were observed, via depth soundings, in large aggregations in depths ranging from 45 to 80 fathoms. Ocean leatherjackets are pelagic egg broadcasters with no parental egg care. Oocytes from ovulated ocean leatherjackets had a mean diameter of 0.66 mm (± S.E. 0.002). The estimated size and age at maturity (L50) for each sex was 352 mm and 2.5+ years old. Mature fish of each sex displayed clear differences in dimorphic and dichromatic features. This research has provided the biological information necessary for future stock assessments of ocean leatherjackets in NSW. In addition, it has contributed to management strategies designed to enhance the sustainability of the ocean leatherjackets fishery.
The biology and fishery of black pomfret Parastromateus niger (Bloch) have been studied for the first time from the northern part of Bay of Bengal along the West Bengal-Orissa Coast. The fish is a carnivore feeding mainly on Acetes, copepods and jellyfishes. The spawning ground is located in the vast shallow continental shelf lying to the north of River Mahanadi along Orissa -West Bengal Coast. The size at first maturity is 28.0 cm SL in males and 30.0 cm SL for females. The sex ratio is close to one. The species contributes to nearly 4.0% f total drift gill-net catch at Chandipur.
Examination of 1108 stomach contents of black pomfret, Parastromateus niger (Bloch, 1795) from October 2003 to September 2004 revealed eight major food groups by a decreasing order of abundance: Bacillariophyceae (23%), fish eggs and larvae (21%), crustaceans (20%), poriferans (15%), annelids (10%), cnidarians (5%), fish scales (4%) and chaetognaths (2%). Copepods were the commonest prey types, with an annual frequency of occurrence of 77%, followed, among the crustaceans, by brachyuran zoea (65%), postlarvae of shrimp (29%) and penaeid shrimps (16%). These were followed by the cnidarians, with hydroid medusae (67%), the annelids, with polychaete larvae (63%), then sponge spicules (poriferans) (54%) and fish scales (45%). Coscinodiscus spp. and Rhizosolenia spp. were the commonest prey types among the phytoplankton diet with frequencies of occurrence of 50% and 40%, respectively. While copepods, brachyuran zoea, chaetognaths, polychaete larvae, sponge spicules and hydroid medusae were ingested throughout the year, the remaining prey types exhibited some seasonal fluctuations. A tow feeding intensity was recorded as the temperature increased from March to August, a period coinciding with the highest number of fish with empty stomachs. Conversely, a greater feeding activity was recorded as the temperature decreased from September to February, a period coinciding with the highest number of fish with 1/2, 3/4 and full stomachs. The proportion of fish eggs and larvae in stomach contents increased significantly with increasing size off. niger, while the proportion of crustaceans significantly decreased with increasing fish size. Although the proportions of poriferans and annelids also decreased with increasing size of P. niger, these decreases were not significant.
The rose bitterling (Rhodeus ocellatus ocellatus, Cyprinidae), a spring and summer breeder, was exposed to various temperature and photoperiod regimes during the different phases of the annual reproductive cycle. In early spring, warm temperature stimulated the recrudescence of the gonads regardless of photoperiod. But during late summer and autumn, a long photoperiod was required to maintain or initiate the gonadal maturation especially at high temperatures (22-28°C). These results indicate that the initiating factor of the breeding season in this species is a rising temperature, whereas the terminating one is the decreasing daylength at high temperatures. Therefore, in the rose bitterling, the responsiveness of the gonads to photoperiod varies clearly with season. The critical photoperiod for maturation falls between 13 and 14hours of light per day. This critical photoperiod could be changed by a pretreatment of artificial photoperiod during the breeding season.
The reproductive activities of the silver pomfret, Pampus argenteus (Euphrasen), in Kuwait waters were investigated from March 1996 to February 1998. Observations on the seasonal distribution of maturity stages and variations in seasonal fluctuations in the gonadosomatic index (GSI) confirmed recent findings that the spawning period begins in May. The species has a prolonged spawning period in the females extending from May to August, whereas the males mature in April and ripe specimens were encountered in monthly samples until September. The recruitment pattern confirmed the one breeding season. There are two spawning peaks, the first in May and the second in August. Variations in GSI relative to fish length indicated that females and males are most fecund at about 24.5–26.4 cm and 20.5–22.4 cm length classes, respectively. The males mature earlier than females, at a minimum size of 12.5–14.4 cm, while the females mature at 20.5–22.4 cm. The oocyte diameter-frequency distribution suggests a serial rhythm of spawning. Fecundity ranged from 28 965 to 455 661 and correlated positively with: (a) standard length (P Document Type: Research Article Publication date: December 1, 2000 (document).ready(function() { var shortdescription = (".originaldescription").text().replace(/\\&/g, '&').replace(/\\, '<').replace(/\\>/g, '>').replace(/\\t/g, ' ').replace(/\\n/g, ''); if (shortdescription.length > 350){ shortdescription = "" + shortdescription.substring(0,250) + "... more"; } (".shortdescription a").click(function() { (".originaldescription").slideDown(); return false; }); }); Related content In this: publication By this: publisher In this Subject: Zoology By this author: Dadzie, S. ; Abou-Seedo, F. ; Al-Shallal, T. GA_googleFillSlot("Horizontal_banner_bottom");
Biological information on N. ayraudi was collected during a survey of demersal fish of the Great Australian Bight between 1978 and 1980. Fish size increased with water depth, the adults were sexually dichromatic, and the sex ratio of female to male was approximately 2 : 1. Though it is a carnivore, N. ayraudi has a digestive tract that is usually associated with herbivores.
Modern ichthyology in Kuwait began nearly 30 years ago with the publication in 1972 of Kuronuma & Abe's Fishes of Kuwait. In it, they listed 130 species spread among 64 families. Two additional books have been published on Kuwait's ichthyofauna, but none has included a complete list of the fishes reported to occur in the country. This paper reviews briefly the history of ichthyology in Kuwait, selected oversights and misidentifications, and provides a current list of fish species using the latest terminology. At present, Kuwait's fish list includes 345 species representing 95 families. The establishment of a national reference collection is suggested in order to maintain voucher specimens and document changes among Kuwait's marine biota due to current irreversible environmental alterations.
The potential annual fecundity of Dover sole becomes fixed before the spawning season when the average diameter of the advanced stock of yolked oocytes exceeds 0.86 mm. About nine batches were spawned over a six-month spawning season (December-May), and spawning ceased when the standing stock of advanced oocytes was exhausted. A 1-kg female released c10 000 eggs per spawning, except for the first and last batches which were smaller than the rest. Near the end of the season, females may spawn more frequently than earlier in the year, increasing the daily production of eggs by the population even though fewer females are reproductively active. Annual reproductive effort of Dover sole was equivalent to c14% of body wet weight per year. Fifty percent of the females had become sexually mature when they reached 332 mm total length. -from Authors
Lake chub obtained from their natural habitat, at three different periods of their annual reproductive cycle, were subjected to four combinations of photoperiod and temperature. Temperature is the major environmental factor controlling spermatogenesis. Higher temperatures (16–21 °C) promote prespermatocytal changes (proliferation of spermatogonia) and hasten or terminate spermiation in prespawning fish; low temperatures (5–12 °C) are essential for normal gonadal proliferation and formation of the primary spermatocytes. Temperature effects are not overridden by either of the two contrasting photoperiods, but at lower temperatures a definite, although slight, photoperiodic effect is evident in the terminal part of all three experiments, Photoperiod does not appear to dominate spermatogenetic processes at any stage. Evidence is presented that an endogenous rhythm of activity is also present and may be partly responsible for the timing of the various testicular changes.
Provinces. PRC landings were 1,228,638 t (44.2% of total ECS land ings), 1,042,233 t (37.5%), 379,403 t (13.6%), and 131,476 t (4.7%), respec ti vel y, for these four provinces, and to talled 2,781,750 t in 1992. The ECS land ings also represented 27.8% oftotal PRC marine landings (9,336,927 t in 1992; China Ministry of Agriculture, 1993). Foreign landings in the ECS are not monitored. Recent estimates suggest that approximately 900,000 t/yr were landed in Taiwan, 400,000 t/yr in the Republic of Korea, and 200,000 t/yr in Japan by overseas fishing vessels oper ating in the ECS for a total foreign catch of 1,500,000 t/yr in the early 1990's.' Total ECS landings in 1992 were there fore about 4,200,000 t of which about 65% were landed by boats based in China. Although adequate data on for eign landings and effort are not avail able, it is important to carry out an as sessment of the ECS landings and fisheries to identify a sustainable manage ment policy for the area and its fisheries.
Using ovaries sampled seasonally from Lake Michigan bloaters in 1968-1969, we determined that one complement or modal group of eggs is produced each year and spawned mainly during January, February, and March. Fecundities estimated for 65 fish taken in October ranged from 3,230 eggs in one medium-size bloater (241 mm long) to 18,768 in the longest (305 mm). We regressed these estimates on lengths and weights of the parental fish to provide a quantitative basis for later evaluating long-term changes in reproductive potential. The resulting rectilinear regression on weight accounted for 75% of the total variation in fecundity.
Monthly changes in mean ova diameter and gonadal weights indicated that spawning of rough shiner, Notropis baileyi, a cyprinid recently introduced in Halawakee Creek (Apalachicola River Drainage), Alabama, occurred during early or middle May through late September or early October. Peak spawning occurred in early or middle June. Several complements of ova matured. Fecundity was linearly related to length and weight of the fish. No significant correlation existed between the diameter of ova and fork length of fish. Versatile food habits, a long successful spawning season and favorable habitat are believed to be the key to the success of this shiner in Halawakee Creek.
Silver pomfret, Pampus argenteus, were collected by fishing with drift gillnets on one spawning ground in Kuwait waters during 1998–2000. Fish size frequency, sex ratio, maturation cycle, spawning frequency, fecundity and egg weight were assessed. The length–weight relationship differed between sexes whereby females were significantly bigger than males. Spawning started in mid-May and continued until early October. During this time the water temperature ranged from 26.0 to 32.8°C, salinity was 39.0‰ and water depth ranged between 5 and 12 m. Large females spawned earlier than young spawners and the overall percentage of males during the spawning period was 70.3%. Spawning occurred after 13.00 h, with peak spawning between 15.00 and 18.00 hours during outgoing tide. Mean daily spawning frequency amounted to 63.2%. Spawning activity was found to be associated with the lunar cycle and spawnings were concentrated during the first and third quarters of the moon period, indicating a semilunar reproduction cycle. It was concluded that a female would spawn at least six times during the season. No change was observed in relative fecundity during the peak spawning season (June–August). Average relative batch fecundity was 176.3 eggs g−1 somatic weight (SW), corresponding to a relative total fecundity of 1058 eggs g−1 SW, which is 1.5 times higher than estimates obtained from counting the standing stock of oocytes. Bigger fish produced heavier eggs and the egg weight decreased as the spawning season progressed. Based on gonadal cycles, oocyte size frequency distribution and total fecundity, we concluded that silver pomfret is a multiple batch spawner with indeterminate fecundity.
Abstract The spawning periodicity of silver pomfret, Pampus argenteus (Euphrasen), was investigated against a background of conflicting evidence on the onset of spawning in this species. Contrary to the existing view that silver pomfret in Kuwait waters begin to spawn in March–April, evidence is presented that indicates a delay in spawning until May. Only an insignificant level of spawning takes place in April which, from the management point of view, may be ignored. The species has a prolonged spawning period extending from May to August in females, although the males mature in April and ripe specimens are encountered in monthly samples until September. There are two spawning peaks, the first one in May and the second in August.
The population dynamics of the black pomfret, Parastromateus niger, sampled from commercial gill-net catches from Kuwaiti waters of the Arabian Gulf, were investigated from October 2003 to September 2005. Length-based stock assessment using the FiSAT software package showed an asymptotic length of 65 cm TL and growth curvature of 0.34 year−1. Raw data as well as that corrected for probability of capture indicated a recruitment from February to September. The total mortality coefficient was estimated to be 1.20, a natural mortality of 0.68 and fishing mortality of 0.52. The selectivity model based on the running average showed that 25% of 14.0 cm TL fish, 50% of specimens reaching 16.3 cm TL, and 75% of all specimens of 20.2 cm TL encountering the gear were retained. Relative yield-per-recruit analyses revealed a current exploitation rate of 0.43; this is below the maximum sustainable yield index, indicating for sustainable fishery of P. niger that the exploitation rate could be increased to 0.6, provided size of the fish at first capture, i.e. the legal size, is also increased to 32.5 cm TL. These results suggest that P. niger stocks in Kuwaiti waters, contrary to existing views, are moderately exploited. This conclusion, however, is critically dependent on the estimate of natural mortality, which requires further confirmation.
Macroscopic and histological studies were carried out to describe the reproductive styles and sex reversal and to follow gonadal changes in captive yellowfin seabream during the second year of life. Four reproductive styles are found in Acanthopagrus latus (Houttuyn, 1782): (i) males and females (gonochorism), (ii) functional males, (iii) transitionals and (iv) functional females. The species is a protandric hermaphrodite and begins life as a functional male with testicular zone undergoing active spermatogenesis, while the ovarian zone is arrested at the primary growth (perinucleolar) phase. Males and females were encountered in virtually all size-classes. Functional males outnumbered the functional females in all size-classes in which they were encountered. Sex reversal begins in the transitionals from July to August, after spawning in the functional males, at 14.9–20.2 cm standard length (SL) and, by November, maturation of the ovarian tissue begins.
A. latus in cages in Kuwait waters spawns from January to April with a peak in February for males, and a peak in March for females and transitionals. Spawning begins in the 18.3–20.2 cm size-range fish, peaking in the 20.3–22.2 cm size-range in both males and females and also in the transitionals, although a few of the latter spawn from 14.9 cm SL. In relation to age, spawning begins at 20 months in males and peaks at 21 months. Females begin to spawn at 21 months with a peak at 22 months, while transitionals generally begin to spawn at 20 months, although a few 14–15-month-old sex-changing individuals were encountered. Temperature, either alone or in combination with other unknown factors, triggers spawning in A. latus.
The present study investigated the growth, mortality, recruitment and food habits ofMonacanthus tomentosus. A total of 1038 specimens were collected by beach seine from the seagrass beds of Kotania Bay (Moluccas, Indonesia) from March 1988 to January 1989. Their length-weight relationship wasW=0.011L
3.242. Based on the von Bertalanffy formula, the asymptotic length,L
, and growth coefficient,K, were determined as 11.79 cm and 0.86, respectively. Total mortality,Z, was low (2.033). Mean length of minimum capturable size (L
c
) was 6.21 cm, and recruitment occurred throughout the year. Food consisted principally of gastropods (21.41%), seagrasses (14.11%), sponges (12.11%), algae (10.82%), amphipods (9.76%) and sedentary polychaetes (9.29%). Pelecypods, opisthobranchs, isopods, copepods, ostracods, foraminiferans, bryozoans, ascidians, nematodes, mollusc eggs and fish eggs were found only in small percentages.
Stock Assessment and Catch prediction of the Filefish, Thamnaconus septentrionalis, with help of Microcomputer
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A preliminary study on the age and growth of filefish (Navodon septentrionalis)
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On the catch of Navodon modestus (Gunther) in the Seto Inland Sea
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On the spawning clusters of the filefish Navodon modestus in the Seto Inland Sea
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On the growth of the File-fish, Navodon modestus, in the Seto Inland Sea
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On an unusually heavy catch of black pomfret, Formio niger by purse seine along Dakshina Kannada coast. Indian Council of Agricultural Research
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Observations on the biology of Parastromateus niger (Bloch) and Pampus chinensis (Euphrasen) from the Godavary Estuary
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Report on a collection of carangoid and formionid fishes from the Huuga Nada area, southern Japan
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fishes from the Huuga Nada area, southern Japan. Bulletin of the Faculty of Agriculture, Miyazaki University
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Rhythm of development in the oocyte of the goldfish, Carassius auratus. Bulletin of the Faculty of Fisheries of Hokkaido University
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Marine Fisheries in Indian Economy
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Trends in development in the prawn fishing techniques in India-A review
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