Fecundity Of Fish Research Articles

Sex dimorphism of Yunnanilus analis and its habitat adaptation in Xingyun Lake, Yunnan, China.

Yunnanilus is a group of endemic fish inhabit in Yun-Gui Plateau and its adjacent areas. They show the characteristic of sex dimorphism, which could be an important reason for their adaptation to karst habitats. Here, we used Yunnanilus analis as the model to understand the sex dimorphism characteristics and its adaptation to the karst habitats. The sex dimorphism, female fecundity, and food specialization of Y. analis were investigated in Xingyun Lake, Jiangchuan, Yunnan. Our results showed that Y. analis exhibit sex size dimorphism (sex dimorphism index=0.23; female with larger body size). There were stains on the transverse sections at females body, but not in males. Males had dark longitudinal lines at their body sides. Morphological differences between males and females were confirmed by the results of one-way analyses of variance (ANOVA), multivariate statistical analyses, principal component analyses, discriminant analyses, and one-way analyses of similarity (ANOSIM) on total length, standard body length, fork length, head width vs. heal length, and the distance between the starting point of ventral fin to the starting point of pectoral fin vs. standard body length. Fecundity of female fish was 1364.5±489.3 (470-2430) eggs, which were positively correlated with their body size. Both female and male Y. analis mainly feed on Chironomid larvae and mayfly naiads. Their food composition was somehow similar, with significantly statistical difference. In conclusion, fecundity selection pressure and food specialization should be the main factors contributing to the evolution of Y. analis' sex dimorphism. More importantly, sex dimorphism of Y. analis is a significant adaptation to the karstic habitats.

Fecundity and food habits of the slender stonebasher (Hippopotamyrus ansorgii Boulenger, 1905) (Mormyridae) in Ogbese river

Fecundity study is important in order to evaluate the reproductive potentials of fish species. Thus, fecundity and food habits of Hippopotamyrus ansorgii (H. ansorgii) from Ogbese river were investigated. Total of 32 specimens of H. ansorgii were used. The major fishing method employed for collecting the specimens were cast and gill netting. Fecundity and food habits the fish were studied. The total lengths ranged from 14.6 cm to 22.1cm while the body weights ranged from 30.0 to 91.0 g. The food items found in the examined stomachs were rotifer, algae, insects, crustacean, detritus and plant parts but the major food items based on the ranking index were insects and crustaceans. The sex ratio of H. ansorgii was 1.13: 1 for males: females. The gonadosomatic index showed that H. ansorgii in Ogbese river uses an average of 11.69% of its body weight in egg production. Fecundity ranged from 600 to 7200 eggs with an average of 3231 eggs per female. In conclusion, H. ansorgii in Ogbese river was an omnivore and highly fecund fish.

РАЗМЕРНО-ВЕСОВАЯ СТРУКТУРА И ПЛОДОВИТОСТЬ АНАДРОМНОЙ СИМЫ (ONCORHYNCHUS MASOU) НА ЗАПАДНОЙ КАМЧАТКЕ

Masu salmon Oncorhynchus masou is the most thermophilic species among the Pacific salmon, and Kamchat-ka peninsula is the northern border of its distribution. Due to small abundance, the biology of this species on the peninsula is poorly studied. Regular scientific researches of Masu salmon in Kamchatka have been con-ducted since 2009. The length-weight structures and fecundity of mature Masu salmon have been analyzed in several streams on western Kamchatka over a 10-year period (from 2009 to 2018) and present time. It has been established that the length, weight and fecundity of mature fish are different in the rivers of the peninsula. A tendency of increasing the biological characteristic of the species in recent years has been noted.

Effects of season and mesh size on the selection of narrow-barred Spanish mackerel, Scomberomorus commerson in the Persian Gulf artisanal gillnet fishery

AbstractIn response to perceived, but unknown variation among the size selection of narrow-barred Spanish mackerel (Scomberomorus commerson) by artisanal gillnetters off Iran, and the need for such data to control exploitation as a precursor to balanced harvesting, the effects of two common mesh sizes (130 and 140 mm stretched mesh opening made from multifilament twine) on catches were investigated over one fishing year (nine months encompassing autumn to spring). Both mesh sizes mostly caught S. commerson at fork lengths (FL) larger than mean sizes at maturity (>67 cm), with the mean size selection incrementally increasing in the 130-mm mesh gillnet from autumn, and especially during spring. The greater selection occurred concurrent with an increasing condition factor (CF) among S. commerson, which typically spawn in late spring/early summer. Conversely, the relative size-selection of the 140-mm mesh gillnet decreased in spring, attributed to increasing CF precluding the capture of larger fish. Such seasonal variation in size selection might be countered by increasing mesh size to ~145 or 150 mm in spring. However, the existing 140-mm mesh might positively affect stock biomass by allowing larger, more fecund fish to avoid capture during spawning. The data support the strong influence of biological and environmental factors on gillnet size selection, which might also extend to other migratory, pelagic species.

Reproductive Biology of Oci Fish Selaroides leptolepis in Tomini Bay

Local people name Selaroides leptolepis distributed in Tomini Bay as Oci Fish. A study of the fish reproductive biology, which is one aspect of fisheries biology, is crucial to support the implementation of sustainable Oci Fish resource management policies. This study aims to determine the average length at first maturity, gonad maturity stages, and fecundity of the fish in Tomini Bay. Sampling was carried out using a stratified random sampling method from the catches of the fishermen landed in Fish Landing Base Kampung Tenda, Gorontalo City. The time interval sampling was conducted per month during April, May, and June 2020. Fish and egg samples preserved using ice cubes and a 10% formaldehyde solution correspondingly. The results of the study showed that the Oci Fish in Tomini Bay had a length range of the first maturity between 166 and 174 mm with a gonad maturity index ranging from 1.773 to 2.760%. The average fish fecundity was 16623 ± 4850 eggs.

Genetic variation in resistance and high fecundity impede viral biocontrol of invasive fish

Abstract Common carp Cyprinus carpio is one of the top global invasive vertebrates and can cause significant ecological damage. The Australian Government's National Carp Control Program (NCCP) proposes to release Koi herpesvirus (KHV) to eradicate feral carp in one of the largest ecological interventions ever attempted. Ecological and human health risks have been highlighted regarding the release of a highly pathogenic viral biocontrol for an aquatic species. The efficacy of KHV has also been questioned, and it has not been demonstrated to produce lasting population reductions. We developed an individual‐based model (IBM) to examine the ecological and evolutionary response of a carp population after KHV release. This simulated the interaction between fish life history, viral epidemiology, host genetic resistance and population demography to critically evaluate the impact of KHV release under optimal conditions and a ‘best‐case scenario’ for disease transmission. KHV will rarely result in prolonged reductions or population extinctions. Crucially, realistic scenarios result in a rapidly rebounding population of resistant individuals. Additional measures aimed to reduce carp population recovery rate (e.g. with genetic engineering) require rapid efficacy to significantly reduce carp numbers alongside KHV. Fish fecundity has an overwhelming influence on viral efficacy as a biocontrol agent when combined with genetic resistance within a population. A high probability of population extinction is only met when carp fecundity is reduced to 1% of biological observations. Synthesis and applications. We use an individual‐based model to evaluate the efficacy of Koi herpesvirus biocontrol in Common Carp, and find that high host fecundity combined with genetic resistance results in rapid population rebound after initial large fish kills. Biocontrol approaches relying on natural selection lose efficacy over successive generations as resistance genes increase in frequency. Given the intense logistical effort and risks to ecosystems and human health associated with large fish kills after viral release, we suggest that sustained manual removal, alongside ecological restoration to favour recovery of native species, provides a risk‐free approach to reducing populations.

Changes induced by atrazine in Clarias gariepinus provide insight into alterations in ovarian histoarchitecture and direct effects on oogenesis

Clarias gariepinus juveniles were exposed to environmentally relevant concentrations of 0 (control), 2.5, 25, 250 and 500 μg L−1 atrazine in a quality-controlled 28-day laboratory procedure. Findings revealed a significant decrease in the levels of follicle-stimulating hormone, luteinizing hormone and prolactin relative to control (p < 0.05). Atrazine reduced the levels of testosterone while increasing the concentration of progesterone. Histologically, the control and treatments presented three stages of oocyte maturation: the chromatin nucleolar oocyte stage, early perinucleolar oocyte stage and the vitellogenic oocyte stage. However, in the ovaries of the treatment group with the lowest treatment concentration (2.5 μg L−1), atretic oocytes with broken membranes invaded many of the dead ova and empty spaces. In other treatments (25, 250 and 500 μg L−1), interfollicular spaces, vacuolation in oocyte formation, and dissolution of oocyte walls were observed. Disruption of the yolk vesicle and clumping of the cytoplasm in maturing oocytes was observed only at the highest atrazine concentration (500 μg L−1). Gross alterations in ovarian histoarchitecture and reproductive hormone levels observed in this study showed interference with oogenesis which may result in reduced egg viability and fecundity in fish with ecological implications in water bodies exposed to atrazine even at reduced concentrations.

Effects of antidepressants in the reproduction of aquatic organisms: a meta-analysis

Pharmaceuticals are widespread contaminants across the aquatic systems and despite the role that these compounds play in society today, little is known about their effects in aquatic organisms once they are released into the environment. This study aims to provide quantitative insight on the effects of antidepressants on the reproduction of fish and crustaceans with a multilevel meta-analysis. A systematic literature search identified 19 studies investigating effects of antidepressant exposure in fish or crustaceans’ reproduction, according to specific selection criteria. Heterogeneity analysis was performed and the moderating effect of the range of exposure concentrations, exposure time, organism group and toxicant was tested. Additionally, publication bias was also addressed. The results showed that, overall, there is no significant association between antidepressant exposure and the reproduction of fish and crustaceans, however, moderator analysis revealed that the range of concentrations is a significant moderator for fish and crustacean fecundity, showing contrary results between the two groups. Antidepressant concentration had a small, yet positive effect on fish fecundity, meaning that increased concentrations resulted in increased fish fecundity, whilst a negative effect on crustaceans’ fecundity was apparent with increasing concentrations. This difference could be related to data artifacts, or, more likely, evidencing a hormetic dose-response curve, with different ranges of exposure concentrations considered in studies on fish and crustaceans. Antidepressants have shown effects on reproductive outcomes in aquatic organisms, based on individual studies and narrative reviews. However, our results show that other factors can have an important role. Additionally, data available for a quantitative assessment is scarce, focusing mainly on a few freshwater species, low concentration ranges and one SSRI compound, fluoxetine. Thus, more research on the subject is needed since meta-analysis are only as statistically powerful as the number of, good quality, studies they include.

Fluctuating temperatures extend median lifespan, improve reproduction and reduce growth in turquoise killifish.

In natural populations, individuals experience daily fluctuations in environmental conditions that synchronise endogenous biorhythms. Artificial alterations of environmental fluctuations can have negative consequences for life history traits, including lifespan. In laboratory studies of aging, the role of fluctuating temperature is usually overlooked and we know little of how thermal fluctuation modulates senescence in vertebrates. In this longitudinal study we followed individually-housed turquoise killifish, Nothobranchius furzeri, from two thermal regimes; ecologically relevant diel fluctuations (20 °C - 35 °C) and stable temperature (27.5 °C), and compared their survival, growth and reproduction. Fish experiencing fluctuating temperatures had a longer median lifespan but reached smaller asymptotic body size. Within-treatment variation indicated that extended lifespan in fluctuating temperatures was not causally linked to decreased growth rate or smaller body size, but occurred solely due to the effect of thermal fluctuations. Male body size was positively associated with lifespan in stable temperatures but this relationship was disrupted in fluctuating thermal regimes. Females exposed to fluctuating temperatures effectively compensated egg production for their smaller size. Thus, there was no difference in absolute fecundity between thermal regimes and body-size corrected fecundity was higher in females in fluctuating temperatures. Overall, despite a brief exposure to sub-optimal thermal conditions during fluctuations, fluctuating temperature had a positive effect on survival and reproduction. These results suggest that the expression of life history traits and their associations under stable temperatures are a poor representation of the relationships obtained from ecologically relevant thermal fluctuations.

Algorithm for an Automated Clarias gariepinus Fecundity Estimation Technique Using Spline Interpolation and Gaussian Quadrature

Fecundity is essential in the field of population ecology, where the number of eggs is measured to get the actual reproductive rate of an organism. The estimation of fecundity is essential for an accurate study of biology and population dynamics of fish species. This estimation can be developed using the gravimetric method (weight method) to calculate the number of eggs. However, this method still requires experienced technicians and much time and effort to compute the number of eggs manually. The increasing growth in both hardware and software have led to many improvements in imaging technology. Hence, this research addresses the problem of employing constructing a computer vision algorithm. This paper introduced the automatic fecundity estimation method, which applied simple mathematic theories and image processing algorithm to estimate the fecundity of African catfish ( Clarias gariepinus ). From the image of the fish, the fish’s eye was be detected using a modified Haar Cascade Classifier Algorithm and appointed axis line where the eye becomes the origin point. Next, we identify the region of interest, which reflects the fish's fecundity to obtain the pixels corresponding to the silhouette of the region as coordinates in Euclidean space, which are then represented with a function using cubic interpolation function. Using this function, we compute the region of interest using an integral numerical approach, e.g., Gaussian Quadrature. From the result, we compared with the ground truth to get the estimation of the number of eggs.

Reproductive cycle, sexual maturity and fecundity of Nemipterus furcosus (Valenciennes, 1830)

Understanding the reproductive biology particularly sexual maturity, reproductive cycle and fecundity of fish is useful for fisheries management. Unfortunately, there is no information about reproductive biology of Nemipterus furcosus. This study addresses this deficit for N. furcosus. We conducted a 12-month study to understand the reproductive biology particularly the sex ratio, sexual maturity, fecundity and reproductive cycle of N. furcosus at the east coast of peninsular Malaysia. Results indicated that ratios of male and female were statistically similar up to 19.0 cm TL (total length). Male outnumbered female above 19.0 cm TL (P < 0.05). The fecundity ranged between 54,970 and 236,938 with a mean fecundity of 102,477 ± 43,580 (standard deviation). Male and female fish reached first sexual maturation at almost same size, 15.8 and 15.6 cm, respectively. This information is needed to determine the lowest acceptable harvest length of this fish under the management aim to enter all female fish for reproduction minimum one time in their life. We estimated the reproductive period of N. furcosus applying oocytes diameter, histological examination of ovaries and monthly mean GSI. All of these methods gave a consistent result about spawning season, which appeared to be from March to July with peaks in March and June. Based on this result, N. furcosus spawners can be protected during March to July for entering the reproductive stock. Apart from artificial breeding, the results of this study might facilitate future efforts at fine-tuning fishing effort for a proper management of N. furcosus.

Influence of Triaenophorus nodulosus invasion on morphobiological parameters of European perch (Perca fluviatilis L.) in Shatsk National Nature Park reservoirs

It was conducted comprehensive ichthyological and ichthyopatological research of European perch (Perca fluviatilis L.) populations in lakes of Shatsk National Nature Park and the impact of Triaenophorus nodulosus invasion on its size, weight and reproductive ability. Morphometric analysis, absolute and relative fecundity of fish were determined by the methods generally accepted in ichthyology. Clinical examination of fish (2,225 specimens, including European perch -1650 specimens) was performed during control catches. Simultaneously, the weight, size, and age of the fish were determined. Morphometric analysis was performed on 120 specimens of perch with the length of 104.4-194.8 mm and the weight of 16.4-177.6 g. Pathoanatomic autopsy of the fish was performed in the field and laboratory conditions. Parasitological studies were performed by the method of incomplete parasitological analysis. The extent and intensity of the invasion were determined. When conducting research on the parasitofauna of native fish species in the lakes of the Shatsk National Nature Park, it was found their infestation with helminths of various systematic positions (Triaenophorus nodulosus, Khawia sinensis, Raphidascaris. acus, and Philometroides lusiana). Perch was the most infected with the helminths. The invasion caused by the plerocercoid of Cestoda T. Nodulosus was the most intensive (18.2-56.3%, depending on the reservoir). There was a significant difference in the measurements of non-infested and infested with T. nodulosus fish individuals of the same age, we also registered significant lag in growth and a decrease in body weight among the infested specimens. A steady trend towards a decrease in fecundity parameters was also observed in infested fish. Thus, in non-infested individuals of 4-year perch, the highest individual absolute fecundity (IAF) was 6.7 thousand eggs against 3.1 thousand eggs in the infested perch (Lucimer lake). The lowest IAF – 3.9 thousand eggs against 2.0 thousand eggs in the infested perch specimesn was found in Chorne Velyke lake. In non-infested individuals of 5-year perch, the highest IAF index was 9.4 thousand eggs when compared to 6.8 thousand in the infested perch (Pulemetske lake). The lowest IAF was 6.3 thousand eggs (Chorne Velyke lake). The highest IAF was recorded in perch from Pulemetske lake (34.6 thousand eggs in non-infested versus 10.3 thousand eggs in infested specimens). The lowest IAF was observed in perch from Chorne Velyke lake (9.1 and 6.6 thousand eggs, respectively). There was decrease in fish size, weight and fecundity in perch infested with Tr. nodulosus, but it did not affect the reproductive fish ability.

PENGARUH INJEKSI HORMON HUMAN CORIONIC GONADOTROPIN (hCG) TERHADAP PERKEMBANGAN GONAD IKAN KEBALI (Oesteochilus Schlegeli Blkr)

The purpose of this study is to determine the optimal dose of hCG homrone on gonad maturation of parent prospective of kebali fish through regular injection. The research was carried out in Aquatic Environment Laboratory of Fisheries and Marine Science Faculty, Universitas Muhammadiyah Pontianak and Floating Net Cage (KJA) in Kelurahan Parit Mayor of Pontianak, that was carried out for 60 days. The expermental design used was a randomized block design (RBD) consisting of 3 groups and each group consisted of 6 treatments. As a treatment is hCG hormone was injected periodically from doses of 0 to 250 IU/kg of fish. Variables observed were Gonad Maturity Level (TKG), Gonado Somatic Index (GSI), Hepato Somatic Index (HSI), fecundity and eggs diameter. The results showed a dose of 150 until 250 IU/kg of fish can reach TKG IV with a greater proportion, a dose of 100 IU/kg of fish can reach TKG III, while the doses below only reach TKG I and II. The average value of HSI in each treatment was 0.74-1.57% and the GSI value is 1.64-4.51% with the highest HSI and GSI achieved at hCG injection with a dose of 150 IU/kg of fish that was with an index value of 1.57% and 4.51% respectively. The average of fish fecundity at hCG hormone doses of 100–150 IU/kg of fish ranged from 11,592–18,059 eggs, with the highest fecundity (18,059 eggs) achieved at the hormone dose of 250 IU/kg of fish. The range of eggs diameter produced after gonad maturation were 0.07–0.37 mm, hCG injection treatments of 150–250 IU/kg generally produces eggs that are 0.24–0.31 mm in size, and the injection dose was 250 IU/kg in part large eggs have a diameter of 0.28–0.31 mm. Water quality during the study was quite supportive for the maturation process of the ovary. Periodic injection of hCG hormone at a dose of 150 IU / kg of fish is the best dose for gonad maturation of kebali fish.

Evaluating sampling strategies for collecting size-based fish fecundity data: an example of Gulf of Maine northern shrimp Pandalus borealis

Evaluating sampling strategies for collecting size-based fish fecundity data: an example of Gulf of Maine northern shrimp <i>Pandalus borealis</i>

Reproduction of Celebes rainbowfish, Marosatherina ladigesi Ahl, 1936 in Pattunuang and Batu Puteh Rivers, South Sulawesi

Marosatherina ladigesi is one of endemic fishes in South Sulawesi and also as ornamental fish. Anthropogenic activities such as destructive fishing and degradation caused by the dredging of sand carried M. ladigesi to the red list of threatened IUCN category as vulnerable species. Accordingly, conservation efforts are needed to maintenance fish population in its habitat. The biologic information for conservation is reproduction of fishes. This research aimed to described reproduction of Celebes rainbow fish including sex ratio, gonad maturity, gonado-somatic index, fecundity, and distribution of egg diameter in Pattunuang and Batu Puteh Rivers, South Sulawesi. This research was conducted from May 2018 to April 2019. The result showed that the sex ratio in Pattunuang and Batu Puteh rivers were 1,00:1,60 and 1,00:1,08, respectively. This species spawned from the end of dry season to the early rainy season. Fecundity of fish in Pattunuang and Batu Puteh rivers were 22-795 eggs and 69-571 eggs, respectively. Based on distribution of egg diameter, Celebes rainbowfish categorized as total spawner. For the conservation of this species is recommended to catch restrictions in the spawning season and for male fish, and needs to be proposed the conservation in situ to determine both of rivers as reservoir area because these habitats are a source of germplasm.

Changes in Shrimping Effort in the Gulf of Mexico and the Impacts to Red Snapper.

Despite a complex management landscape and decades of overfishing, Red Snapper (Lutjanus campechanus) stocks have grown substantially in the Gulf of Mexico and restrictions on the fisheries that catch them are being loosened. This year, annual shrimping effort was allowed to increase by 21% after National Marine Fisheries Service scientists concluded that the resulting bycatch of Red Snapper would only reduce the annual allowable catch in other fisheries by ∼1% and have no impact on population growth. Nonetheless, the recreational fishing sector intensely campaigned against this rule, fueled by wild mischaracterization of shrimp trawl bycatch in media outlets targeting anglers. Here, we aim to elevate the debates surrounding Red Snapper management by presenting scientific and historical context for the potential impacts from shrimping. We discuss our views of the current problems facing Red Snapper and key ecological questions to address for more effective management of this resource.

Fecundity of Atlantic sturgeon ( Acipenser oxyrinchus Mitchill, 1815) captured by the commercial fishery in the Saint John River, New Brunswick, Canada

Knowledge of fecundity in fishes is important for understanding life history, modeling population dynamics, developing fisheries management and determining conservation status. Sturgeon species are known for their high fecundity but to date only two populations of Atlantic sturgeon (Acipenser oxyrinchus Mitchill, 1815) have been examined for this aspect of their biology. The species is protected in most regions of eastern North America but the Saint John River, New Brunswick supports one of the two remaining commercial fisheries in Canada. Sixty females selected by this fishery were sampled for total length, weight, age, gonad weight and egg number. Absolute fecundity ranged from 153,630 to 1,306,626 eggs, with a mean fecundity of 582,832 ± 261,806 eggs. Absolute fecundity exhibited a significant positive relationship to increasing body weight but not to total length or age. Relative fecundity ranged from 129 to 216 eggs/g gonad weight and although it declined with both increasing body size and age the relationships were not significant. The Gonadosomatic Index (GSI) ranged from 1.3% to 27.0% with a mean of 7.8% ± 4.94 SD. Relative fecundity found in this study was higher and mean GSI lower than reported for other Atlantic sturgeon populations and other sturgeon species. Differences were probably due to location of the fishery downstream from spawning sites and selection of pre-spawning females by the commercial fishery.

Selection for increased male size predicts variation in sexual size dimorphism among fish species.

Variation in the degree of sexual size dimorphism (SSD) among taxa is generally considered to arise from differences in the relative intensity of male-male competition and fecundity selection. One might predict, therefore, that SSD will vary systematically with (1) the intensity of sexual selection for increased male size, and (2) the intensity of fecundity selection for increased female size. To test these two fundamental hypotheses, we conducted a phylogenetic comparative analysis of SSD in fish. Specifically, using records of body length at first sexual maturity from FishBase, we quantified variation in the magnitude and direction of SSD in more than 600 diverse freshwater and marine fish species, from sticklebacks to sharks. Although female-biased SSD was common, and thought to be driven primarily by fecundity selection, variation in SSD was not dependent on either the allometric scaling of reproductive energy output or fecundity in female fish. Instead, systematic patterns based on habitat and life-history characteristics associated with varying degrees of male-male competition and paternal care strongly suggest that adaptive variation in SSD is driven by the intensity of sexual selection for increased male size.

The gonad maturity and fecundity of toman fish (Channami cropeltus) during rainyseason to dry season periode in Rawa Danau Panggang waters, Hulu Sungai Utara Regency, South Kalimantan, Indonesia

This study objectives to evaluation the level of gonad maturity and fecundity of toman fish living in the habitat of swamp waters Danau Panggang, Hulu Sungai Utara Regency, South Kalimantan during the transition season period (rainy to dry season). Fish sampling were carried out every month for six month from April to September 2018. The determining method of the sampling location used an analytical survey method. The result showed the ratio sex male : female = 55.8% : 44.2%, the weight range of 0.18 to 32.2 gram and the level gonad maturity varied form Gonad Maturity Level (GMI) I – IV, increase from rain season to dry season. The opportunity for have mature gonads base on weight is more than 1.90 kg. Fecundity result obtained 5.24% (rain season) to 60.35% (dry season). This data shows that toman fish can spawn throughout the year with peaks in the dry season.

Influences of female body condition on recruitment success of walleye (Sander vitreus) in Wisconsin lakes

Stock reproductive potential informs population dynamics and response to harvest. Indices of body condition, like relative weight (Wr), may indicate individual energetic state and provide a mechanistic link between spawning stock traits and recruitment. We tested for relationships among Wr of three female size classes (381–456, 457–557, and ≥558 mm total length), reproductive traits, and age-0 recruitment using data from 92 walleye (Sander vitreus) populations in the Ceded Territory of Wisconsin during 1989–2015 and a lake-specific time series from Escanaba Lake, Wisconsin, during 1958–2014. In Escanaba Lake, Wr was positively related to maturation in small females and was positively related to fecundity and gonadosomatic index in intermediate fish. Among and within populations, Wr demonstrated compensatory density dependence and positive relationships with growing degree-days. Recruitment was positively related to large female Wr variation across lakes and negatively related to small female Wr variation in Escanaba Lake. Improving the condition of large female walleye may promote recruitment, and Wr may serve as an accessible metric of reproductive potential in walleye stock–recruit analyses.