Modelling the population dynamics of an exploited, tropical fish species playing a fundamental role in aquatic ecosystems

Ecology Of Freshwater Fish, Journal Year: 2023, Volume and Issue: 32(2), P. 477 - 487

Published: Jan. 12, 2023

Abstract The coporo, Prochilodus mariae , plays a fundamental role in aquatic ecosystems as detritivorous species facilitating the flow of carbon to rest ecosystem's food web. It is also one most exploited freshwater fish species. Fishing, pollution and environmental changes Orinoquia region Colombia have considerably reduced its population size. We analysed dynamics P. during an annual river cycle, including extreme drought flood scenarios, by means mathematical model simulations. we propose novel because it relates biological, ecological factors dynamics, reproduction, growth size biomass fish, recruitment, predation, fishing mortality flow. proposed apparently gives approximate description for 2010 good fit catch data that year was obtained. simulations showed first 3 months are crucial this when affected combination fishing, biological which increase natural (e.g. upstream migration predation) low flow). Hypothetical scenarios show local extinction could occur if were decrease.

Language: Английский

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Rapid changes in age structure, mortality, and escapement accompanied stock recovery of the estuarine Red Drum population of Texas

Marine and Coastal Fisheries, Journal Year: 2023, Volume and Issue: 15(5)

Published: Oct. 1, 2023

Abstract Objective We analyzed a fishery‐independent catch time series in the context of predicted historical age structure Red Drum Sciaenops ocellatus for years 1980–2019. This roughly coincided with closure commercial fishery Texas (in 1981) and federal waters 1987). Changes size were used to estimate changes mortality offshore escapement. Methods Otoliths collected from between 1997 2015 create seasonal length‐at‐age growth functions, which then ages (based on total length) all encountered gill‐net samples by Parks Wildlife Department during 1980–2019 (total n = 311,150). Temporal observed body overall predict annualized mean age, mortality, escapement estuarine population. Result The initial 14‐year period (1980–1993) was characterized rapid increases per hour length (mm) samples, followed relative stability remainder series. There 55% increase estimated when comparing 1980 (mean 0.84 year) 2019 (1.30 years). also significant declines ( Z ; via curves) (estimated indirectly mortality) recovery period. Conclusion current population is significantly larger older than it at onset management measures, annually well above target level 30% set fisheries plan. These findings suggest that regulations put into effect starting 1980s have succeeded recovering Texas.

Language: Английский

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A longline survey for spurdog distribution and life history along the Norwegian coast

Fisheries Management and Ecology, Journal Year: 2023, Volume and Issue: 31(2)

Published: Dec. 21, 2023

Abstract To improve spatiotemporal data collection and inform future spurdog Squalus acanthias stock assessment, a new dedicated longline survey was initiated in 2021 coastal waters of southern Norway. The comprised mixture randomly predefined stations to facilitate unbiased abundance estimates supplementary including informant putative hotspots. During 25 days autumn 2021, 287 were sampled, which 280 categorized as “satisfactory” terms gear quality deployment. Spurdog catches ( n = 954) more abundant southeast shallower (19–150 m). No length, sex, or maturity stratified schooling behavior found with increasing catches. Females larger than males, but males older. Growth reproduction parameters within ranges reported for the stock. Our results provide valuable input designs regards optimizing boat time, location stations, biological sampling protocols. provides important monitoring other data‐limited species, especially considering newly re‐opened fishery also study possible effects climatic changes on distribution.

Language: Английский

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Stochastic modelling and synthesis of dynamic fish recruitment productivity in the Celtic Seas ecoregion

ICES Journal of Marine Science, Journal Year: 2023, Volume and Issue: 80(9), P. 2329 - 2341

Published: Sept. 26, 2023

Abstract The Celtic Seas ecoregion (CSE) is undergoing climatic and ecosystem changes, which can induce changes in fish productivity. Globally, the productivity of many stocks has shown evidence change over decadal timescales. Varying factors might drive these dynamics CSE, but for stocks, mechanisms have not been fully understood to be included management advice. We study dynamic 28 by tracking integrated stochastic signals relationship between stock size recruitment using state-space modelling applying Peterman’s Productivity Method. Our research objectives were (i) fit Ricker stock–recruitment models with time-varying parameters all age- or length-based assessed (ii) evaluate vary time, (iii) examine temporal characteristics historical productivity, (iv) correlation across stocks. For 22 out at least one three parameter had a better than time-invariant model. In diverse patterns, some displaying relevant long-term decreasing trends. Getting insight into very valuable important implications sustainable fisheries.

Language: Английский

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Variations in life-history traits in exploited and unexploited populations of Perth herring (Nematalosa vlaminghi): evidence for density-dependent growth?

Marine and Freshwater Research, Journal Year: 2024, Volume and Issue: 75(3)

Published: Feb. 20, 2024

Context Fishing can reduce population biomass, allowing remaining individuals to grow faster and mature earlier because of greater resource availability, which potentially compensates for lost reproductive output over a shortened lifespan resulting from fishing mortality. Aims To compare life-history traits Nematalosa vlaminghi, long-lived (20 years), semi-anadromous fish endemic south-western Australia, in exploited unexploited populations living similar environments. Methods Populations were sampled 2016–2018. Total mortality (Z) was estimated using catch-curve analyses, annual recruitment variability. Maturation age length by logistic regression analysis. Growth curves fitted length-at-age data. Key results Compared the population, Z 2.6 times greater, juvenile growth more than twice as fast, maturity attained at least 3 years population. Conclusions Results supported hypothesis density-dependent processes. Environmental factors may also have contributed trait differences between populations. Implications Faster maturation partly compensate populations, although severe truncation owing is still likely decrease resilience this species, irrespective any compensatory

Language: Английский

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