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Detrended recent growth (DRG) during the last two complete days prior to collection of blue marlin (n = 134) and sailfish (n = 130) larvae \9 mm SL according to percentage of prey type in gut. Prey types were a copepods in the genus Farranula and b cladocerans in the genus Evadne. Blue marlin with [66.6% Farranula in their guts grew faster than larvae with \33.3 and 33.3-66.6% Farranula in their guts (ANCOVA: P = 0.002; Bonferroni multiple comparison). No other comparisons were significant

Detrended recent growth (DRG) during the last two complete days prior to collection of blue marlin (n = 134) and sailfish (n = 130) larvae \9 mm SL according to percentage of prey type in gut. Prey types were a copepods in the genus Farranula and b cladocerans in the genus Evadne. Blue marlin with [66.6% Farranula in their guts grew faster than larvae with \33.3 and 33.3-66.6% Farranula in their guts (ANCOVA: P = 0.002; Bonferroni multiple comparison). No other comparisons were significant

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Atlantic blue marlin (Makaira nigricans) and sailfish (Istiophorus platypterus) larvae were collected from 10monthly cruises (June–October 2003 and 2004) across the Straits of Florida to test (1) whether growth differed between the more productive western region near the Florida shelf, and the less productive eastern region toward the Bahamas, and...

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... blue marlin: P = 0.703; sailfish: P = 0.670). For \9 mm blue marlin, DRG was significantly related to the proportion of Farranula in their gut: larvae with [66.6% Farranula in their guts exhibited significantly faster recent growth that those with \33.3% or 33.3-66.6% Farranula in their guts (ANCOVA: P = 0.002; Bonferroni multiple comparison; Fig. 6). The opposite trend toward lower growth with higher proportions of Evadne in the gut was not significant for blue marlin (ANCOVA: P = 0.131; Bonferroni multiple comparison; Fig. 5). There were no significant differences in DRG for \9 mm sailfish for either diet group (ANCOVA: Evadne: P = 0.242; Farranula: P = 0.226; temperature ...

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... Beyond total carbon ingested, a proxy for energy intake, feeding success is also modulated by the capacity of ingested prey taxa to provide the suite of essential nutrients, such as amino acids and fatty acids, that are necessary for proper larval development (Rønnestad et al., 1999;Sargent et al., 1999). The larval prey field is composed of various taxa characterized by differences in potential to fulfill requirements relative to energy and essential nutrient intake, which likely explains why several larval fish species have been shown to selectively consume prey taxa that result in their optimal growth (Robert et al., 2009;Sponaugle et al., 2010;Murphy et al., 2013). These considerations make it important to identify larval fish prey to the lowest taxonomic resolution possible. ...
... While relatively few studies have empirically demonstrated a relationship between feeding success and growth in larval fishes (Dower et al., 2009;Robert et al., 2014b;and Pepin et al., 2015), even fewer studies have investigated the relationship between growth and the contribution of preferred prey to feeding success (Robert et al., 2009;Sponaugle et al., 2010;Murphy et al., 2013). The paucity of knowledge of larval prey preferences from highly resolved taxonomical information, and how this absence of data may be affecting our capacity to predict recruitment, has been increasingly acknowledged in recent years (St. ...
... John et al., 2001;Robert et al., 2014a). A positive relationship between consumption of a larva's preferred prey and recent growth has been documented for fish species inhabiting various environments (Atlantic mackerel, Robert et al., 2009; Atlantic blue marlin [Makaira nigricans], Sponaugle et al., 2010;snapper [Chrysophrys auratus], Murphy et al., 2012). In both Atlantic mackerel and blue marlin, consumption of the preferred prey during early larval development, before the onset of piscivory, determined whether an individual would be characterized by fast or slow growth trajectory during the next stages of development (Robert et al., 2009;Sponaugle et al., 2010). ...
Article
Year-class strength of fish stocks is often set during the larval stage, with fast growth being a favourable factor leading to strong recruitment. Following 30 years of poor recruitment, redfish (Sebastes sp.) in the Gulf of St. Lawrence (GSL) produced unprecedentedly strong year classes in 2011–2013. The relationship between larval diet and growth that potentially drove these successful recruitment events is unknown. Gut content and otolith microstructure of redfish larvae collected from the GSL in 1999 and 2000 were analysed in order to understand the relationship between recent feeding success and growth in larval redfish, and identify feeding behaviours that are associated with fast growth. Growth was positively correlated with larval body depth (BD), which was used as a morphological proxy for growth. Prey type and size were the best explanatory variables of larval BD after obligatory first-feeding. Larvae that consumed large naupliar stages of frequently consumed copepod taxa were deeper-bodied and grew more quickly than larvae that consumed redfish’s preferred prey, Calanus finmarchicus eggs.Warming GSL waters have shifted the phenology of commonly consumed prey taxa earlier in the season, whichmay increase the overlap between redfish and naupliar prey that drive fast growth, survival, and potentially recruitment success.
... A distinctive feature of this species was the occurrence of two microstructural zones in otoliths: a first zone where primary increments were more homogeneous and easy to identify, in contrast with a second zone where ring's alignment and other perturbations predominated. Microstructural zones in sagittal otoliths of YOY have been reported in several teleost fish (Wellington and Victor 1989;Beldade et al. 2007;Sponaugle et al. 2010;Garcia-Seoane et al. 2015), particularly in demersal and reef-associated fish (Victor 1986;Wilson and McCormick 1997;Sponaugle et al. 2010). These features have been linked roughly with the larval stage, the transition from larval to juvenile stages or habitat transitions, and later juvenile stages where juveniles occur in nursery areas or deeper habitats (Jenkins and May 1994;Raventos and Macpherson 2001;Plaza et al. 2001;Mansur et al. 2014). ...
... A distinctive feature of this species was the occurrence of two microstructural zones in otoliths: a first zone where primary increments were more homogeneous and easy to identify, in contrast with a second zone where ring's alignment and other perturbations predominated. Microstructural zones in sagittal otoliths of YOY have been reported in several teleost fish (Wellington and Victor 1989;Beldade et al. 2007;Sponaugle et al. 2010;Garcia-Seoane et al. 2015), particularly in demersal and reef-associated fish (Victor 1986;Wilson and McCormick 1997;Sponaugle et al. 2010). These features have been linked roughly with the larval stage, the transition from larval to juvenile stages or habitat transitions, and later juvenile stages where juveniles occur in nursery areas or deeper habitats (Jenkins and May 1994;Raventos and Macpherson 2001;Plaza et al. 2001;Mansur et al. 2014). ...
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Age estimates were made on otoliths of 32 young-of-the-year (YOY) Barracuda, Sphyraena viridensis Cuvier (1829), captured in the south-western Mediterranean Sea. Increments were observed in Barracuda sagittae sectioned in a transverse plane and viewed with light microscopy. Increment counts were made for age estimation. Estimated ages ranged from 27 to 299 days of fish ranging in size from 15.9 to 38.9 cm total length (TL). The observed mean growth rate is 3.487 mm.day−1. Decreasing growth performance is evidenced according to age: 3.822 mm.day−1 between 159 and 302 mm (27–139 days), 1.596 mm.day−1 between 352 and 389 mm (172–299 days).
... Nine species: yellowfin tuna (Thunnus albacares), blue marlin (Makaira nigricans), bigeye tuna (Thunnus obesus), white marlin (Kajikia albidus), swordfish (Xiphias gladius), sailfish (Istiophorus albicans), bluefin tuna (Thunnus thynnus), albacore tuna (Thunnus alalunga), and skipjack tuna (Katsuwonus pelamis) were each divided into two-stage multi-stanza groups (juvenile and adult) to account for ontogenetic changes in diet and fishing selectivity. Larval conspecifics were included in the juvenile life stage, as tuna and billfish larval stages are much shorter than one year and growth rates are rapid (Fromentin and Powers, 2005;Sponaugle et al., 2010). The age of each multi-stanza division was determined by the age at maturity referenced in stock assessments. ...
Article
Ecosystem-based modeling is rapidly becoming an established technique to investigate the health and stability of ecosystems. In the Gulf of Mexico, ecosystem models are applied to neritic systems, but less focus has been placed on the oceanic domain. Since 2011, severe declines have been observed in many micronekton groups that occupy the mesopelagic zone (200-1000 m depth). Here we present an ecosystem model for the oceanic northern Gulf of Mexico for the year 2011, simulate that model according to micronekton trends through 2018, and quantify the top-down and bottom-up impacts that each functional group has on one another. These trends were examined to determine whether interactions between the two groups have changed directionally over time. In 2011, zooplankton (trophic level =2) occupied greater than one-third of the total metazoan biomass, and also 40% of the total energy throughput ascended to higher trophic levels in the system. Of the 1849 possible functional group interactions (most of which are indirect), approximately 27% showed significant changes between 2011 and 2018, which were related to shifts in biomass and diet throughout the simulation. Direct top-down interactions changed more frequently than other types of trophic relationships. The frequency of direct changes that occurred in the simulation was not observed evenly among all functional groups, as opposed to indirect interactions. These changes between functional group interactions can be used to further examine potential shifts in the trophic structure of marine ecosystems under various forcing scenarios.
... Anderson, 1994;Robert et al., 2008;Voss et al., 2009;Demontigny et al., 2012;Murphy et al., 2012;Llopiz and Cowen, 2008). Successful feeding on preferred prey species generally results in high larval growth and survival (Robert et al., 2009;Sponaugle et al., 2010;Murphy et al., 2013). Given the importance of preferred prey taxa in driving variability in growth and survival potential, it is essential to investigate prey selectivity during the larval stage as a first step towards the robust assessment of recruitment-relevant bottom-up processes in a given population (Robert et al., 2014). ...
... There is increasing evidence that many fish species exhibit strong prey preference and selectivity during the larval stage (Robert et al., 2008). In selective species, larvae that feed successfully on preferred prey are characterized by faster growth, which increases their probability of survival (Robert et al., 2009;Sponaugle et al., 2010;Murphy et al., 2013). Various potential consumable prey taxa occur within a given zooplankton assemblage, but in order to optimize growth and survival, larvae should preferentially feed on taxa that are abundant, easily captured, and provide the highest net gain of energy and essential nutrients (Schoener, 1971;Werner and Hall, 1974). ...
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Spatiotemporal overlap between fish larvae and their planktonic prey is an important source of recruitment variability. Over the past decade, one species of redfish, Sebastes mentella, from the Gulf of St. Lawrence (GSL) produced multiple strong cohorts following decades of low recruitment, which has generated strong interest in identifying potential drivers of larval survival. The present study provides the first detailed, multi-year assessment of larval redfish (Sebastes spp.) trophodynamics. Interannual variability in larval redfish diet composition and prey selectivity was assessed using high-resolution prey identification of larval gut contents and in situ prey fields. Eggs from the calanoid copepod Calanus finmarchicus represented the most frequently consumed prey in 3 of the 4 collection years, and contributed the largest proportion of carbon ingested by redfish larvae in all years. The high consumption of C. finmarchicus eggs by larvae, combined with evidence of positive selection for this taxon in some years, supports the hypothesis of a strong trophic link between larval redfish and a key calanoid copepod in the GSL ecosystem. Our results indicate that future efforts investigating GSL redfish recruitment processes should consider environment-driven variability in the reproductive phenology and abundance of C. finmarchicus.
... Nine species: yellowfin tuna (Thunnus albacares), blue marlin (Makaira nigricans), bigeye tuna (Thunnus obesus), white marlin (Kajikia albidus), swordfish (Xiphias gladius), sailfish (Istiophorus albicans), bluefin tuna (Thunnus thynnus), albacore tuna (Thunnus alalunga), and skipjack tuna (Katsuwonus pelamis) were each divided into two-stage multi-stanza groups (juvenile and adult) to account for ontogenetic changes in diet and fishing selectivity. Larval conspecifics were included in the juvenile life stage, as tuna and billfish larval stages are much shorter than one year and growth rates are rapid (Fromentin and Powers, 2005;Sponaugle et al., 2010). The age of each multi-stanza division was determined by the age at maturity referenced in stock assessments. ...
Presentation
Although they likely dominate the world’s total fish biomass, the roles of mesopelagic fishes in oceanic ecosystems are poorly represented in ecosystem models. Mesopelagic fishes are occasionally practiced as commercial species, but restrictions due to fishing cost and gear selectivity have stunted global production. Many mesopelagic fishes undertake a diel vertical migration where they ascend to the near-surface waters during the night to feed and descend into the depths during the day. Other mesopelagic fishes remain at depth throughout the diel cycle. Apex predators (e.g., tunas, marine mammals, sharks) make routine dives to prey on micronekton in the mesopelagic zone (200 – 1000 m depth). Here we introduce an ecosystem model of the oceanic Gulf of Mexico and emphasize the trophic impact that mesopelagic fishes have on other functional groups within the system. This model has been coupled with a biogeochemical model (ROMS-NPZD), compared to 39 time series, and validated with a Monte Carlo procedure. Mesopelagic fishes occupy a secondary consumer role in the ecosystem (trophic level 3.3 – 4.0), where feeding guilds range from zooplanktivores to micronektonivores. In total, mesopelagic fishes occupy greater than 80% of the total energy pathways that progress from primary producers to apex predators. Lanternfishes are an important prey species for juvenile tunas and dragonfishes. Based on predator and prey groups, hatchetfishes and lanternfishes both occupy a similar niche to pelagic cephalopods (another important prey group to apex predators). Mesopelagic fishes are prey to upper-trophic level organisms and consume zooplankton, potentially providing wasp-waist control in oceanic ecosystems.
... A low nutrient concentration from clean water discharge from the dam, working interactively with a low water temperature from hypolimnetic discharge, may induce low productivity and a shortage of food availability for fish (Garnier et al. 2002;Sponaugle et al. 2010). No research had been conducted investigating impacts of dam release on primary productivity and plankton downstream the TGD. ...
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Drifting larval fish assemblages were investigated at three sections in the middle reach of the Yangtze River downstream of the Three Gorges Dam to reveal recovery gradients and to identify the major environmental factors influencing their temporal and spatial patterns. Larval fish in the river section closest to the dam showed lower abundance, later occurrence, narrower temporal niche breadth, and more pairs of dominant species with high niche overlap than those further from the dam. Water temperature, transparency, and discharge significantly influenced the larval fish assemblages. They showed longitudinal gradients of increased water temperature, decreased transparency, and increased discharge in a downstream direction. Our results suggested that hypolimnetic and clean water discharge from the dam heavily impacted larval fish assemblage in the river section near the dam. With an increased distance to the dam and the input of some major tributaries, this impact was gradually buffered, thus forming the longitudinal recovery gradients. We suggest that priority for conservation should shift from river sections closer to the dam to those further from the dam.
... Within a population, larval growth can vary spatially (e.g. Suthers et al., 1989;Sponaugle et al., 2010) and interannually (e.g. Olafsdottir and Anderson, 2010;Murphy et al., 2013;Rodríguez-Valentino et al., 2015;Takahashi et al., 2016). ...
Article
We examined larval capelin density and growth dynamics in two relatively unstudied northern coastal embayments of Newfoundland (White Bay and Notre Dame Bay), comparing these larval characteristics to those measured in the annually-surveyed Trinity Bay in order to assess the spatiotemporal variability in larval dynamics and its potential implications on subsequent recruitment. We conducted ichthyoplankton surveys in August of 2015 and 2016, assessing larval density and using otolith microstructure analyses to estimate larval age and growth rates. Size of larvae captured over the two years ranged between 4 and 17 mm, corresponding to an estimated age of 1–33 d. Our results indicated substantial spatial and interannual variability in both density and growth. Larval density was similar between bays in 2015 but drastically different in 2016, where the northern bays were characterized by an order of magnitude less larvae than Trinity Bay. Larval growth was significantly higher in the northern bays in 2015, but lower in 2016, relative to Trinity Bay. This spatiotemporal variability in growth, abundance, and survival potential of larval capelin indicates that the proportion of recruits originating from these key spawning areas fluctuates interannually, with potential implications for the assessment and management of the stock.
... These studies suggest that fast-growing larvae tend to show continuously more rapid growth and consequently a high survival probability. The feeding habits and growth of larval Atlantic billfish and sailfish were investigated, and it was suggested that the early occurrence of piscivory and fast growth induced by piscivory could be important for their survival (Sponaugle, Walter, Denit, Llopiz & Cowen, 2010). The survival of larval Pacific bluefin tuna depends largely on their growth in the very early stage of their life history (6-13 DAH), which is the stage before the occurrence of piscivory (Satoh et al., 2013;Tanaka et al., 2006). ...
Article
In mass culture of Pacific bluefin tuna Thunnus orientalis, yolk-sac larvae of other species are fed as a major prey item to tuna larvae from 7 to 8 mm in total length. Marked growth variations in tuna larvae are frequently observed after feeding of yolk-sac larvae, and this variation in the growth of tuna larvae is subsequently a factor leading to the prevalence of cannibalistic attacks. To elucidate details of the mortality process of hatchery-reared tuna larvae after the initiation of yolk-sac larvae feeding, we compared the nutritional and growth histories of the surviving (live) tuna larvae to those of the dead fish, found dead on the bottom of the tank, as direct evidence of their mortality processes. Cause of mortality of tuna larvae 3 and 5 days after the initiation of feeding of yolk-sac larvae was assessed from nitrogen stable isotope and otolith microstructure analyses. Stable isotope analysis revealed that the live fish rapidly utilized prey fish larvae, but the dead fish had depended more on rotifers relative to the live fish 3 and 5 days after the initiation of feeding of yolk-sac larvae. The growth histories based on otolith increments were compared between the live and dead tuna larvae and indicated that the live fish showed significantly faster growth histories than dead fish. Our results suggest that fast-growing larvae at the onset of piscivory could survive in the mass culture tank of Pacific bluefin tuna and were characterized by growth-selective mortality.
... Larval fish are therefore more effective in capturing passive prey, which can include the eggs of fish and invertebrates, and particulate organic materials. Indeed, although these prey are frequently captured by fish at all life stages, they make up the overwhelming majority of larval fish diets (Hillgruber et al., 1995;Holzman and Genin, 2003;Kent et al., 2006;Sponaugle et al., 2010). ...
Article
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Suction-feeding is thought to be the primary mode of prey capture in most larval fishes. Similar to adult suction-feeders, larvae swim towards their prey while rapidly expanding their mouth cavity to generate an inward flow of water that draws the prey into the mouth. Although larvae are known to experience flows with lower Reynolds numbers than adults, it is unclear how the suction-induced flow field changes throughout ontogeny, and how such changes relate to prey capture performance. To address these questions, we determined mouth dimensions and opening speeds in Sparus aurata from first-feeding larvae to adults. We proceeded to develop a computational model of mouth expansion in order to analyze the scaling of suction flows under the observed parameters. Larval fish produced suction flows that were ~2 orders of magnitude slower than those of adults. Compared to adult fish, in which flow speed decays steeply with distance in front of the mouth, flow speed decayed more gradually in larval fish. This difference indicates that viscous forces in low Reynolds number flows modify the spatial distribution flow speed in front of the mouth. Consequently, simulated predator-prey encounters showed that larval fish could capture inert prey from a greater distance compared to adults. If prey attempted to escape, however, larval fish performed poorly: simulations inferred capture success in only weakly escaping prey immediately in front of the mouth. These ontogenetic changes in Reynolds number, suction-induced flow field, and feeding performance may explain a widespread ontogenetic diet shift from passive prey at early life stages to evasive prey as larvae mature.
... Additionally, of the scombroid taxa examined, nearly all have been observed to be piscivorous during the larval stage (i.e. they consume other fish larvae), with Scomberomorus often displaying piscivory at first-feeding (Finucane et al., 1990;Shoji and Tanaka, 2001). A piscivorous feeding behavior is likely necessary for larvae to fuel their rapid growth rates and high metabolic demands in the warm waters in which they occur (Govoni et al., 2003;Sponaugle et al., 2010;Tanaka et al., 1996). ...
Article
Scombroid fishes, including tunas, mackerels, and billfishes, constitute some of the most important fisheries in lower latitudes around the world. Though the early life stages of these taxa are relatively well-studied, worldwide patterns in larval feeding dynamics and how such patterns relate to environmental conditions are poorly resolved. We present a synthesis of feeding success (i.e. feeding incidences) and diets of larval scombroids from around the world, and relate these results to water column and sea surface properties for the several regions in which larval feeding studies have been conducted. Feeding success of larval tunas was shown to be distinctly different among regions. In some locations (the Straits of Florida and the Mediterranean Sea), nearly no larvae had empty guts, whereas in other locations (the Gulf of California and off NW Australia) ~40–60% of larvae were empty. Diets were consistently narrow in each region (dominated by cyclopoid copepods, appendicularians, nauplii, and other fish larvae), and were usually, but not always, similar for a given scombroid taxon among regions (though diets differed among taxa). Larval habitat conditions were often similar among the 9 regions examined, but some clear differences included low levels of eddy kinetic energy and cooler waters (at the surface and at depth) in the Mediterranean, and lower chlorophyll concentrations around the Nansei Islands, Japan and off NW Australia where feeding success was low. When observed zooplankton abundances are also taken into account, the compiled results on feeding and environmental conditions indicate a bottom-up influence on feeding success. Moreover, the variability among regions highlights the potential for region-specific mechanisms regulating larval survival and, ultimately, levels of adult recruitment.