The age,growth rates and length to weight relationships for the south-eastern Australian population of largehead hairtail(Trichiurus lepturus)were investigated for the first time.Age was estimated by counting annuli i...The age,growth rates and length to weight relationships for the south-eastern Australian population of largehead hairtail(Trichiurus lepturus)were investigated for the first time.Age was estimated by counting annuli in sectioned sagittal otoliths,with a maximum age of 8 years estimated for males and females.We found no sig-nificant differences in the growth rates of males and females over the size(12–78 cm pre-anal length(PL))and age(0–8 years)ranges sampled.However,females in our collection were larger on average than males,and all fish sampled>60 cm PL were female,suggesting that females may grow to larger sizes than males and that sampling of greater numbers of larger and older fish may be required in future.T.lepturus growth was described by the von Bertalanffy growth function parameters L_(∝)=74.89 cm PL,K=0.13yr^(-1)and t0=0.80 yr,with the L_(∝)being amongst the largest reported for the species.Growth was variable,with the sizes at any given age spanning up to 50 cm PL.Female T.lepturus increased in body weight relative to length faster than males,as has been reported in other populations.The length/weight relationship for the south-eastern Australian population was significantly different,with almost no overlap,from that reported for T.lepturus in the Arabian Sea.The substantial differences in growth rates,maximum sizes and body morphometrics of T.lepturus from south-eastern Australia in comparison to other populations globally are consistent with the hypotheses that it represents a distinct population,although investigations using additional population markers are required to verify this.展开更多
Knowledge of reproductive biology and life-history traits of populations exploited by fisheries is important for their sustainable management.We investigated the life-history traits of Trichiurus lepturus(largehead ha...Knowledge of reproductive biology and life-history traits of populations exploited by fisheries is important for their sustainable management.We investigated the life-history traits of Trichiurus lepturus(largehead hairtail)in south-eastern Australia;a region of low exploitation for this otherwise heavily exploited circumglobal species,to investigate whether there were differences in the reproductive biology and life-history traits in the south-east Australian population compared with those in other regions.We also used histological sections to examine male and female gonads at a microscopic level.Trichiurus lepturus in south-eastern Australia had a greater maximum length(193 cm total length(TL)),matured at a larger length(108 cm TL at 50%mature)and had a spawning period(March to September,Austral winter)that was inconsistent with other regions.The overall sex ratio of 1:0.4 females:males was consistent with a female dominant sex ratio observed in other regions,particularly in larger length classes.However,females in the current study dominated samples from both estuarine and coastal habitats,as well as during the spawning and non-spawning periods,which is not consistent with the patterns found in other regions.Differences in south-eastern Australia may relate to limited fishing pressure,genetic variation,or differences in environmental factors that influence reproductive development,including temperature,trophic resources and habitat.展开更多
基金supported by funding from the NSW Saltwater Recreational Fishing Trust(grant number SS022),Western Sydney University,and the NSW Department of Primary Industries.
文摘The age,growth rates and length to weight relationships for the south-eastern Australian population of largehead hairtail(Trichiurus lepturus)were investigated for the first time.Age was estimated by counting annuli in sectioned sagittal otoliths,with a maximum age of 8 years estimated for males and females.We found no sig-nificant differences in the growth rates of males and females over the size(12–78 cm pre-anal length(PL))and age(0–8 years)ranges sampled.However,females in our collection were larger on average than males,and all fish sampled>60 cm PL were female,suggesting that females may grow to larger sizes than males and that sampling of greater numbers of larger and older fish may be required in future.T.lepturus growth was described by the von Bertalanffy growth function parameters L_(∝)=74.89 cm PL,K=0.13yr^(-1)and t0=0.80 yr,with the L_(∝)being amongst the largest reported for the species.Growth was variable,with the sizes at any given age spanning up to 50 cm PL.Female T.lepturus increased in body weight relative to length faster than males,as has been reported in other populations.The length/weight relationship for the south-eastern Australian population was significantly different,with almost no overlap,from that reported for T.lepturus in the Arabian Sea.The substantial differences in growth rates,maximum sizes and body morphometrics of T.lepturus from south-eastern Australia in comparison to other populations globally are consistent with the hypotheses that it represents a distinct population,although investigations using additional population markers are required to verify this.
文摘Knowledge of reproductive biology and life-history traits of populations exploited by fisheries is important for their sustainable management.We investigated the life-history traits of Trichiurus lepturus(largehead hairtail)in south-eastern Australia;a region of low exploitation for this otherwise heavily exploited circumglobal species,to investigate whether there were differences in the reproductive biology and life-history traits in the south-east Australian population compared with those in other regions.We also used histological sections to examine male and female gonads at a microscopic level.Trichiurus lepturus in south-eastern Australia had a greater maximum length(193 cm total length(TL)),matured at a larger length(108 cm TL at 50%mature)and had a spawning period(March to September,Austral winter)that was inconsistent with other regions.The overall sex ratio of 1:0.4 females:males was consistent with a female dominant sex ratio observed in other regions,particularly in larger length classes.However,females in the current study dominated samples from both estuarine and coastal habitats,as well as during the spawning and non-spawning periods,which is not consistent with the patterns found in other regions.Differences in south-eastern Australia may relate to limited fishing pressure,genetic variation,or differences in environmental factors that influence reproductive development,including temperature,trophic resources and habitat.
