The ecological characteristics of four lizardfishes, Trachinocephalus myops, Saurida undosquamis, Saurida tumbil and Saurida elongata, were studied from specimens （910 T. myops, 454 S. un-dosquamis, 686 S. tumbil and...The ecological characteristics of four lizardfishes, Trachinocephalus myops, Saurida undosquamis, Saurida tumbil and Saurida elongata, were studied from specimens （910 T. myops, 454 S. un-dosquamis, 686 S. tumbil and 744 S. elongata） collected monthly in the southern Taiwan Straits from April 2005 to March 2006. The population dynamics of the four lizardfishes was also discussed by the comparison with the previous studies. All being composed of 7 a classes; the dominant group of T. myops and S. tumbil was 1–2 a, while S. undosquamis and S. elongate were 2–3 a. The total mortality coefficient Z and the fishing mortality F were at high as indicated by the exploitation ratio E（0.5）, and a large number of by-caught juvenile and young fishes showing that the stock of lizardfishes in this area was overexploited and the fishing gear was irrational. Compared with the previous studies, the maximum and mean fork length, body mass and age of the four lizard- fishes declined gradually, the lizardfishes populations were younger in age and smaller in size. The asymptotic fork length L ∞ decreased while increasing growth coefficient k, and age at the inflexion point of mass t r was younger compared with the previous studies. The declining of older ones has moderated the feeding competition and the younger ones grew faster. The larger mortality param-eters Z, M and F have revealed higher fishing pressure. The smaller change of the first mature fork length of female T . myops and the change from K selection pattern to r selection pattern of S. tumbil have indicated a more vulnerable fishery ecosystem in this area. The changes of ecological characteristics and population dynamics may be caused by over-exploitation of demersal fishes such as the lizardfishes, especially a large number of juvenile and young fishes by-catch by the current fishing gears and methods. Therefore, in addition to the traditional fishery management approach such as the minimum length-limit, ecosystem approach to fisheries management （EAF） 展开更多
<span style="font-family:Verdana;">This study was used</span><span style="font-family:Verdana;"> to</span><span style="font-family:;" "=""><...<span style="font-family:Verdana;">This study was used</span><span style="font-family:Verdana;"> to</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> lift nets and trap net fishing at intertidal zone of lagoon and estuarine regions of southern Taiwan. From July 2013 to July 2018, a total 420 specimens of </span><i><span style="font-family:Verdana;">Pisodonophis</span></i><span style="font-family:Verdana;"> were analyzed, the average total body length (TL) and average body weight (W) of </span><i><span style="font-family:Verdana;">P</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">boro</span></i><span style="font-family:Verdana;"> eels are 68.4 ± 11.9 cm and 140.4 ± 86.1 g (N = 194), respectively. Typically, </span><i><span style="font-family:Verdana;">P</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">cancrivorus</span></i><span style="font-family:Verdana;"> eels are smaller (TL = 52.8 ± 9.2 cm) and lighter (W = 107.9 ± 73.7 g [N = 119]) than </span><i><span style="font-family:Verdana;">P</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">boro</span></i><span style="font-family:Verdana;"> eels. The natural logarithmic linear relationships between the TL and W of </span><i><span style="font-family:Verdana;">P</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">boro</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">P</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">cancrivorus</span></i><span style="font-family:Verdana;"> are respectively expressed as ln(W)</span><sub><span style="font-family:Verdana;">b</span></sub><span style="font-family:Verdana;"> = 2.4405 ln(TL) <span style="white-space:nowrap;">−</span> 5.4448 (R</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> = 0.796, N = 19展开更多
基金Marine Public Welfare Project of China under contract Nos 200805065,200905019-6,200705029 and 200805064Chinese Off shore Investigation and Assessment under contract No.908-02-04008+1 种基金the Scientific Research Foundation of the Third Institute of Oceanography,SOA under contract No.2011006Marine Science Foundation for Young Scientist under contract No.2011143
文摘The ecological characteristics of four lizardfishes, Trachinocephalus myops, Saurida undosquamis, Saurida tumbil and Saurida elongata, were studied from specimens （910 T. myops, 454 S. un-dosquamis, 686 S. tumbil and 744 S. elongata） collected monthly in the southern Taiwan Straits from April 2005 to March 2006. The population dynamics of the four lizardfishes was also discussed by the comparison with the previous studies. All being composed of 7 a classes; the dominant group of T. myops and S. tumbil was 1–2 a, while S. undosquamis and S. elongate were 2–3 a. The total mortality coefficient Z and the fishing mortality F were at high as indicated by the exploitation ratio E（0.5）, and a large number of by-caught juvenile and young fishes showing that the stock of lizardfishes in this area was overexploited and the fishing gear was irrational. Compared with the previous studies, the maximum and mean fork length, body mass and age of the four lizard- fishes declined gradually, the lizardfishes populations were younger in age and smaller in size. The asymptotic fork length L ∞ decreased while increasing growth coefficient k, and age at the inflexion point of mass t r was younger compared with the previous studies. The declining of older ones has moderated the feeding competition and the younger ones grew faster. The larger mortality param-eters Z, M and F have revealed higher fishing pressure. The smaller change of the first mature fork length of female T . myops and the change from K selection pattern to r selection pattern of S. tumbil have indicated a more vulnerable fishery ecosystem in this area. The changes of ecological characteristics and population dynamics may be caused by over-exploitation of demersal fishes such as the lizardfishes, especially a large number of juvenile and young fishes by-catch by the current fishing gears and methods. Therefore, in addition to the traditional fishery management approach such as the minimum length-limit, ecosystem approach to fisheries management （EAF）
文摘<span style="font-family:Verdana;">This study was used</span><span style="font-family:Verdana;"> to</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> lift nets and trap net fishing at intertidal zone of lagoon and estuarine regions of southern Taiwan. From July 2013 to July 2018, a total 420 specimens of </span><i><span style="font-family:Verdana;">Pisodonophis</span></i><span style="font-family:Verdana;"> were analyzed, the average total body length (TL) and average body weight (W) of </span><i><span style="font-family:Verdana;">P</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">boro</span></i><span style="font-family:Verdana;"> eels are 68.4 ± 11.9 cm and 140.4 ± 86.1 g (N = 194), respectively. Typically, </span><i><span style="font-family:Verdana;">P</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">cancrivorus</span></i><span style="font-family:Verdana;"> eels are smaller (TL = 52.8 ± 9.2 cm) and lighter (W = 107.9 ± 73.7 g [N = 119]) than </span><i><span style="font-family:Verdana;">P</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">boro</span></i><span style="font-family:Verdana;"> eels. The natural logarithmic linear relationships between the TL and W of </span><i><span style="font-family:Verdana;">P</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">boro</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">P</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">cancrivorus</span></i><span style="font-family:Verdana;"> are respectively expressed as ln(W)</span><sub><span style="font-family:Verdana;">b</span></sub><span style="font-family:Verdana;"> = 2.4405 ln(TL) <span style="white-space:nowrap;">−</span> 5.4448 (R</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> = 0.796, N = 19
