Recruitment In Fish Populations Research Articles

Fish Population Recruitment 2: Stock Recruit Relationships and why they matter for stock assessment

A good understanding of stock recruitment is essential for accurate stock assessment and good fisheries management. But recruitment and how it is used can be difficult to understand. This publication uses a recent Florida spotted seatrout stock assessment as an example to show how the stock-recruit relationship allows managers to determine whether or not a given fish population is overfished.

Fish Population Recruitment: What recruitment means and why it matters

Recruitment, the process by which small fish transition to older, larger life stages, is probably the most important process that regulates populations of fish, but it is complicated to understand. This 6-page fact sheet written by Edward V. Camp, Robert N. M. Ahrens, Angela B. Collins, and Kai Lorenzen and published by the UF/IFAS Program in Fisheries and Aquatic Sciences, School of Forest Resources and Conservation explains the recruitment process in fish populations and why recruitment is so important to fisheries science and management. https://edis.ifas.ufl.edu/fa222

Egg and Larval Collection Methods Affect Spawning Adult Numbers Inferred by Pedigree Analysis

AbstractAnalytical methods that incorporate genetic data are increasingly used in monitoring and assessment programs for important rate functions of fish populations (e.g., recruitment). Because gear types vary in efficiencies and effective sampling areas, results from genetic‐based assessments likely differ depending on the sampling gear used to collect genotyped individuals; consequently, management decisions may also be affected by sampling gear. In this study, genetic pedigree analysis conducted on egg and larval Lake Sturgeon Acipenser fulvescens collected from the St. Clair–Detroit River system using three gear types was used to estimate and evaluate gear‐specific differences in the number of spawning adults that produced the eggs and larvae sampled (Ns), the effective number of breeding adults (Nb), and individual reproductive success. Combined across locations and sampling years, pooled estimates were 330 (Ns; point estimate) and 317 (Nb; 95% CI = 271–372). Mean reproductive success was 4.35 with a variance of 5.33 individuals/spawner. Mean ± SE estimated numbers of unique parents per genotyped egg or larva (i.e., adult detection rate) from 2015 samples were 1.140 ± 0.003 for vertically stratified conical nets, 0.836 ± 0.002 for D‐frame nets, and 0.870 ± 0.002 for egg mats. Using samples from 2016, adult detection rates were 0.823 ± 0.001 for D‐frame nets and 0.708 ± 0.001 for egg mat collections. Coancestry values were negatively correlated with adult detection rate. Although genetic pedigree analyses can improve the understanding of recruitment in fish populations, this study demonstrates that estimates from genetic analyses can vary with the targeted life stage (a biologically informative outcome) and sampling methodology. This study also highlights the influence of sampling methods on the interpretation of genetic pedigree analysis results when multiple gear types are used to collect individuals. Development of standardization approaches may facilitate spatial and temporal comparisons of genetic‐based assessment results.

Effects of seawater acidification and cadmium on the antioxidant defense of flounder Paralichthys olivaceus larvae

Increasing atmospheric carbon dioxide has led to a decrease in the pH of the ocean, which influences the speciation of heavy metals and consequently affects metal toxicity in marine organisms. To investigate the effects of seawater acidification and metals on the antioxidant defenses of marine fishes, the flounder Paralichthys olivaceus, was continuously exposed to cadmium (Cd; control, 0.01 and 0.15 mg L−1) and acidified seawater (control (pH 8.10), 7.70 and 7.30) for 49 days from embryogenesis to settlement. The results demonstrated that both Cd and acidified seawater could induce oxidative stress and consequently cause lipid peroxidation (LPO) in the larvae. Antioxidants (i.e., superoxide dismutase, SOD; catalase, CAT; reduced glutathione, GSH; glutathione S-transferase, GST; glutathione peroxidase, GPx; and glutathione reductase, GR) functioned to defend the larvae against oxidative damage. Overall, Cd induced (SOD, GST and GSH) or inhibited (CAT and GPx) the enzymatic activities or contents of all the selected antioxidants except for GR. The antioxidants responded differently to seawater acidification, depending on their interaction with the metal. Similarly, the mRNA expressions of the antioxidant-related genes were upregulated (sod, gr and gst) or downregulated (cat and gpx) in response to increasing Cd exposure. Seawater acidification did not necessarily affect all of the biomarkers; in some cases (e.g., SOD and sod, GR and gr), Cd stress may have exceeded and masked the stress from seawater acidification in regulating the antioxidant defense of the larvae. The integrated biomarker response (IBR) was enhanced with increasing levels of the stressors. These findings support the hypothesis that seawater acidification not only directly affects the antioxidant defense in flounder larvae but also interacts with Cd to further regulate this defense. This study has ecological significance for assessing the long-term impacts of ocean acidification and metal pollution on the recruitment of fish populations in the wild.

A length-based mark-recapture model for estimating abundance and recruitment: Removing bias due to size-selective capture gear

We describe an unbiased length-based, age-structured mark-recapture (LAMR) model for estimating length-based abundance and recruitment of fish populations. Many mark-recapture studies employ capture gear that is size-selective, leading to a larger and faster growing marked sub-population with a different capture probability than the unmarked sub-population, resulting in a basic violation of assumptions for many mark-recapture models. Persistent differences in marked and unmarked individuals are estimated in our model using growth-type group accounting. Simulation-evaluation results indicate that the model produces largely unbiased estimates of recruitment and abundance across a range of sampling scenarios and population life-history types, and is robust to growth parameter misspecification. However, in older, slow growing populations, the model is prone to ‘smearing’ of recruitment estimates across early year-classes. The LAMR model is applied to data from multiple wild populations of rainbow trout to estimate recruitment and abundance. Overall, results indicate that the LAMR model addresses shortcomings associated with using size-selective gear in mark-recapture studies to produce reliable estimates of recruitment and size-based abundance.

Diet Composition and Feeding Habits of Two Engraulid Fish Larvae (Engraulis Japonicus and Coilia Nasus) in the Nakdong River Estuary, Korea

Choi, H.C.; Youn, S.H.; Huh, S.-H., and Park, J.M., 2018. Diet composition and feeding habits of two engraulid fish larvae (Engraulis japonicus and Coilia nasus) in the Nakdong River estuary, Korea. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 346–350. Coconut Creek (Florida), ISSN 0749-0208.Engraulis japonicus and Coilia nasus are members of the family Engraulidae, and their larvae are important components in the estuarian ecosystems that they inhabit. The dietary study of fish larvae is essential to understanding early survival and recruitment in fish populations. This study investigated the dietary compositions and size-related dietary changes in E. japonicus and C. nasus larvae in the Nakdong River estuary. Larvae samples were collected monthly between April and August 2011 using an RN80 net at two stations in the estuary. Gut content analyses revealed that E. japonicus fed mostly on copepods, and secondarily on tintinnids and cladocerans, while C. nasus preferred to consume freshwater cladocerans. These dietary differences between the two larvae were closely related with habitat preference, which provided different local prey sources at each station. As the larvae of both species grew, the consumption of copepods for E. japonicus, and cladocerans for C. nasus, gradually increased, indicating distinct ontogenetic dietary changes. This dietary study of larval E. japonicus and C. nasus is important information for the development of fisheries, and can be implemented in related further studies of areas other than estuaries.

Fatty acid content of eggs determines antipredator performance of fish larvae

Recent work has suggested that provisioning of eggs with certain critical nutrients could be a more meaningful measure of maternal investment and correlate of offspring fitness than traditional measures of egg size. The aim of our study was to assess variability in egg quality and larva quality and to identify connections between them and the implications for larval survival. Egg size, proximate composition, and fatty acid composition were measured for 40 batches of eggs from 8 captive pairs of red drum (Osteichthyes: Sciaenops ocellatus). We reared larvae from these batches of eggs to a common size (10mm total length, 2–3weeks posthatching) and assessed routine activity and escape response performance of 671 individuals. Egg fatty acid composition varied more than egg size or proximate composition. Concentrations of certain long chain, highly unsaturated essential fatty acids (e.g., arachidonic acid and docosahexaenoic acid) were the only egg traits that were significantly related to larva quality (measured as escape performance). Reduced escape performance of larvae from eggs with low fatty acid concentrations was not compensated by 3weeks of feeding on a diet enriched with fatty acids, suggesting irreversible developmental effects. Since fatty acids in eggs originate from the maternal diet, offspring survival may be determined in part by availability of nutrient-rich prey to pre-spawning adults. Migrations, regime shifts, and exploitation of marine communities could operate through this mechanism to influence recruitment in fish populations. Our findings underscore the importance of non-genetic maternal contributions to egg quality and the linkage between environmental conditions experienced by adult females and offspring fitness.

Relative larval loss among females during dispersal of Lake Sturgeon (Acipenser fulvescens)

Mortality that occurs during larval dispersal as a consequence of environmental, maternal, and genetic effects and their interactions can affect annual recruitment in fish populations. We studied larval lake sturgeon (Acipenser fulvescens) drift for two consecutive nights to examine whether larvae from different females exposed to the same environmental conditions during dispersal differed in relative levels of mortality. We estimated proportional contributions of females to larval collections and relative larval loss among females as larvae dispersed downstream between two sampling sites based on genetically determined parentage. Larval collections were composed of unequal proportions of offspring from different females that spawned at upstream and downstream locations (~0.8 km apart). Hourly dispersal patterns of larvae produced from females spawning at both locations were similar, with the largest number of larvae observed during 22:00–23:00 h. Estimated relative larval loss did not differ significantly among females as larvae were sampled at two sites approximately 0.15 and 1.5 km from the last section downstream of spawning locations. High inter- and intra-female variation in larval contributions and relative larval loss between nights may be a common feature of lake sturgeon and other migratory fish species, and likely is a source of inter-annual and intra-annual variation in fish recruitment.

Pattern of recruitment variability in the geographical range of the exploited northeast Atlantic fish species

It has long been argued that populations living on the edges of the species geographical range should exhibit stronger environmentally imposed variations in abundances than populations living near the centre of this range. This so-called ‘Species Range Hypothesis’ is tested here for the recruitment of 62 marine fish populations of the northeast Atlantic, belonging to 17 species. The pattern of increasing recruitment variability from the centre towards the edges of the species range was modelled by a quadratic linear regression between an index of interannual variability in recruitment and an index of population position in species range. The relationship between recruitment variability and exploitation rate was also investigated. A wide range of recruitment variability was observed among the 62 populations. The expected latitudinal pattern of recruitment variability was significant when populations of the various species were pooled in the same analysis. At the species level, this pattern was found for most species, but was significant only for cod and sole. Recruitment variability was also dependent on the number of years in the time series, although this association did not perturb the relationship with population position. The analysis did not show any clear impact of fishing on recruitment variability. These results suggest that the influence of environment on the recruitment of fish populations is stronger for populations living on the edges of the species geographical range than for populations living at the centre of this range.

An Assessment of the Potential for Selenium to Impair Reproduction in Bull Trout, Salvelinus confluentus, from an Area of Active Coal Mining

Selenium (Se) is an essential nutrient, but in higher concentrations can reduce recruitment in fish populations by increasing rates of deformities during early development. Recent work has identified elevated levels of Se in water and biota collected downstream from coal mining activity in Alberta's northeast slopes region. We also recently identified increased incidence of terata and edema in rainbow trout and brook trout with elevated tissue Se from this area. However, there is currently no information regarding the potential for Se to contribute to declining stocks of bull trout, a species of concern in the area. The present study provides an assessment of the potential for Se to contribute to low recruitment in bull trout downstream from coal mining activity. Non-destructive muscle biopsy sampling and a sensitive atomic fluorescence analysis technique are used to determine Se. Results indicate that most bull trout (>90%) captured immediately downstream from coal mining activity in the region have concentrations of Se that would be expected to impair recruitment. Additional work is required to determine the extent of Se's contribution to low recruitment in bull trout.

Verifying Residuals from Catch Curves to Detect Recruitment Variation in Largemouth Bass and Crappies

Residuals associated with catch-curve regressions can represent variable recruitment in fish populations, but the use of this method to quantify recruitment variation has not been verified. I computed age-0 and age-1 catch rates of crappies Pomoxis spp. collected with trap nets set in the fall in three Alabama reservoirs and the age-1 catch rate of largemouth bass Micropterus salmoides captured with electrofishing during spring over a 13-year period in a single Georgia reservoir. These indices of juvenile abundance were correlated (r = 0.52–0.81, P < 0.01) to residuals generated from catch-curve regressions for electrofishing data collected when these same year-classes recruited to the fishery at age 3 and older. At higher age-0 crappie and age-1 largemouth bass catch rates, these relations became curvilinear, and improved fit was computed with data transformation and nonlinear fits to the data. An asymptotic relation was observed between age-0 and age-1 catch rates for the same crappie year-classes, and an inverse relation was evident between mean length at age 1 and juvenile crappie catch rates. This result suggested that density-dependent growth suppression and mortality occurred, as age-0 fish did not proportionally recruit to the age-3+ fishery. However, the age-1 crappie (about 18 months old) catch rate was linearly related (r2 = 0.48–0.55; P < 0.01) to residuals when data were compared separately for each reservoir, which suggested that full recruitment to the population occurred at this age. For largemouth bass, mean length at age 1 was positively related to age-1 catch rate, and recruitment of strong year-classes to the fishery appeared proportionally greater than for abundant age-0 crappies. Residuals generated from catch-curve regressions can serve as a useful quantitative index of juvenile crappie and largemouth bass abundance that can be used in subsequent analyses to explain recruitment variation. However, in some instances, initial strong year-class abundance may not be fully expressed in the fishery later in life.

Contributions to ecology from the study of recruitment in fish populations

Contributions to ecology from the study of recruitment in fish populations

Towards a Science of Recruitment in Fish Populations.David H. Cushing

<i>Towards a Science of Recruitment in Fish Populations.</i>David H. Cushing

Towards a Science of Recruitment in Fish Populations

Towards a Science of Recruitment in Fish Populations

BOOK REVIEWS

Journal of Fish BiologyVolume 51, Issue 6 p. 1270-1275 BOOK REVIEWS First published: 01 April 2005 https://doi.org/10.1111/j.1095-8649.1997.tb01143.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract EARLY LIFE HISTORY AND RECRUITMENT IN FISH POPULATIONS. Edited by R. Christopher Chambers and Edward A. Trippel. RÉSULTATS DES CAMPAGNES MUSORSTOM, VOLUME 17. Edited by Bernard Séret. BASELINE STUDIES OF BIODIVERSITY: THE FISH RESOURCES OF WESTERN INDONESIA. Edited by D. Pauly and P. Martosubroto. MOLECULAR SYSTEMATICS OF FISHES. Edited by Thomas D. Kocher and Carol A. Stepien. FISHES OF CHESAPEAKE BAY. By Edward O. Murdy, Ray S. Birdsong and John A. Musick. Volume51, Issue6December 1997Pages 1270-1275 RelatedInformation

Simple application of using residuals from catch-curve regressions to assess year-class strength in fish

Residuals associated with catch-curve regressions can represent variable recruitment in fish populations. Catch curves are used to estimate steady-state mortality and assume relatively constant recruitment, but this assumption is rarely met. I documented the presence of abundant year classes of largemouth bass ( Micropterus salmoides), from earlier sampling and these dominant year classes persisted over time in two reservoirs. I expanded simple linear catch-curve regressions that used age (in years) as an independent regressor to multiple regression models each of which incorporated an additional independent environmental variable (ENVIR) that was measured when fish were age 0. The age term in the regression was proportionally weighted to the sample size at each age which deflated the influence of older and rarer fish in the analysis. This generalized regression equation: log e (NUMBER) = b 0 − b 1 (AGE) ± b 2 (ENVIR); explained variable abundance-at-age (NUMBER) and the environmental term was related to the formation of weak and strong year classes after accounting for the effects of age. Typically, age will explain the majority ( r 2 ≥ 0.5) of the variation in abundance-at-age. For two largemouth bass populations, environmental hydraulic variables were significant ( P < 0.10) terms in this equation and explained an additional 12 and 16% of the variation in number after accounting for the variation explained by age. For data collected in one population 2 yrs after the initial analysis, the same strong and weak year classes persisted, residuals from these catch curves were correlated ( r = 0.86, P < 0.05, N = 6), and the influence of hydrology on year class formation was duplicated. This approach can provide savings in labor and funds as abundance of young fish or recruitment indices do not have to be measured each year.

New Books

Kroodsma, D. E. &amp; Miller, E. H. (eds) 1996: Ecology and evolution of acoustic communication in birsds.Rigler, F. J. &amp; Peters, R. H. 1995: Science and limnology.Cushing, D. H. (1996): Towards a science of recruitment in fish populations.Hausmann, K. &amp; Hösmann, N. 1996: Protozoology. 2nd edition, with contributions by H. Machemer, M. Mulisch, and G. Steinbrück.Sommer, U. 1996: Algen, Quallen, Wasserfloh‐Die Welt des Planktons, Springer Verlag, Berlin, Heidelber, New York.

Towards a science of recruitment in fish populations

Towards a science of recruitment in fish populations

BOOK REVIEWS

Books reviewed in this article:TOWARDS A SCIENCE OF RECRUITMENT IN FISH POPULATIONS. By David H. Cushing.

D.H. Cushing Towards a science of recruitment in fish populations, xix, 175p. Nordbünte, Germany: Ecology Institute, 1996. (Excellence in Ecology no. 7). Price DM 58.

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