In the present paper, a study of the productivity of oocytes in 402 female individuals of the horse mackerel, Trachurus trachurus for an interval of fork length （LF） between 14 cm and 20 cm, in stage IV （pre-spawn...In the present paper, a study of the productivity of oocytes in 402 female individuals of the horse mackerel, Trachurus trachurus for an interval of fork length （LF） between 14 cm and 20 cm, in stage IV （pre-spawning） and V （spawning） was performed to estimate the fecundity rate in Oran Bay （Algerian western coast） since October 2008 to April 2009. Total fecundity （absolute and relative） were calculated using fish length, weight and eviscerated weight of gonads. Absolute fecundity by size class oscillates from 33,375 to 56,391 eggs with an average of 48,686 ±11,470. The relative fecundity ranges from 34,802 to 139,636 eggs per 100 g body weight with an average of 96,955 ± 33,814 and it is varying between 15,544 and 46,561 per gram of gonad with an average of 28,595 ±20,251. The distribution of oocytes shows that stages I and II are presented throughout the spawning season and they constitute a stockpile for subsequent clutches.展开更多
Pelagic fish are the most abundant species in upwelling regions,contributing 25%of total global fisheries production.Climate-driven changes in the marine environment play a crucial role in their population dynamics.Us...Pelagic fish are the most abundant species in upwelling regions,contributing 25%of total global fisheries production.Climate-driven changes in the marine environment play a crucial role in their population dynamics.Using Chilean jack mackerel(Trachurus murphyi)as an example,this study conducted simulations to quantify the impacts of environmental variations on the stock assessment.A habitat-based surplus production model was developed by integrating suitable habitat area into the model parameters carrying capacity(K)and intrinsic growth rate(r),with a suitable habitat area serving as the proxy for the environmental conditions for Chilean jack mackerel in the Southeast Pacific Ocean.The dynamics of Chilean jack mackerel stock and fisheries data were simulated,and four assessment models with different configurations were built to fit simulated data,with or without considering environmental effects.The results indicated that Joint K-r model,which integrated both parameters with the suitable habitat area index,outperformed the others by coming closest to the‘true'population dynamics.Ignoring habitat variations in the estimation model tended to overestimate biomass and underestimate harvest rate and reference points.Without observation and process error,the results were estimated with bias,while FMSY is relatively sensitive.This research illustrates the importance to consider random errors and environmental influences on populations,and provides foundation guidelines for future stock assessment.展开更多
文摘In the present paper, a study of the productivity of oocytes in 402 female individuals of the horse mackerel, Trachurus trachurus for an interval of fork length （LF） between 14 cm and 20 cm, in stage IV （pre-spawning） and V （spawning） was performed to estimate the fecundity rate in Oran Bay （Algerian western coast） since October 2008 to April 2009. Total fecundity （absolute and relative） were calculated using fish length, weight and eviscerated weight of gonads. Absolute fecundity by size class oscillates from 33,375 to 56,391 eggs with an average of 48,686 ±11,470. The relative fecundity ranges from 34,802 to 139,636 eggs per 100 g body weight with an average of 96,955 ± 33,814 and it is varying between 15,544 and 46,561 per gram of gonad with an average of 28,595 ±20,251. The distribution of oocytes shows that stages I and II are presented throughout the spawning season and they constitute a stockpile for subsequent clutches.
基金supported by the National Key Research and Development Program of China(No.2019YFD0901404)。
文摘Pelagic fish are the most abundant species in upwelling regions,contributing 25%of total global fisheries production.Climate-driven changes in the marine environment play a crucial role in their population dynamics.Using Chilean jack mackerel(Trachurus murphyi)as an example,this study conducted simulations to quantify the impacts of environmental variations on the stock assessment.A habitat-based surplus production model was developed by integrating suitable habitat area into the model parameters carrying capacity(K)and intrinsic growth rate(r),with a suitable habitat area serving as the proxy for the environmental conditions for Chilean jack mackerel in the Southeast Pacific Ocean.The dynamics of Chilean jack mackerel stock and fisheries data were simulated,and four assessment models with different configurations were built to fit simulated data,with or without considering environmental effects.The results indicated that Joint K-r model,which integrated both parameters with the suitable habitat area index,outperformed the others by coming closest to the‘true'population dynamics.Ignoring habitat variations in the estimation model tended to overestimate biomass and underestimate harvest rate and reference points.Without observation and process error,the results were estimated with bias,while FMSY is relatively sensitive.This research illustrates the importance to consider random errors and environmental influences on populations,and provides foundation guidelines for future stock assessment.
