Population Dynamics of American Plaice (Hippoglossoides platessoides) off West Greenland (NAFO Divisions 1B–1F), 1982–94
Growth, mortality, stock composition by sex, age distribution and female sexual maturity were determined for American plaice (Hippoglossoides platessoides) off West Greenland for the first time. Examination of otoliths revealed that females grew at a faster rate than males. Growth rates were observe...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.518.8223 http://archive.nafo.int/open/studies/s30/Lloret.pdf |
| Summary: | Growth, mortality, stock composition by sex, age distribution and female sexual maturity were determined for American plaice (Hippoglossoides platessoides) off West Greenland for the first time. Examination of otoliths revealed that females grew at a faster rate than males. Growth rates were observed to be lower than those of adjacent stocks of American plaice (NAFO Div. 3M, Div. 3LNO). The length at 50 % maturity and age at 50 % maturity values for females were estimated to vary between 25.5 and 26.5 cm and at a corresponding age around 8 years. A trend of decreasing fish age with increasing latitude suggested the existence of nursery grounds in the northern area off West Greenland. No indications for different distributions by depth were found. During 1982–94, a severe decline of the American plaice stock off West Greenland in abundance and biomass was observed. Until 1987, the survey indices were found to vary at a high level. In 1988, the decline of both abundance and biomass was most pronounced and the following period until 1990 was characterized by nearly continuous losses. During 1990–94, young fish (0–6 years old) dominated the stock population, contributing 70 % to total stock abundance in 1994. The recently depleted status of the American plaice stock off West Greenland was reflected by significant reductions in mean age from 7.8 years in 1982 to 5.8 years in 1994. Older age groups suffered the biggest losses during the entire period 1982–94 when relative values were considered. Losses were reflected by high total and fishing mortality coefficients, which were usually higher than the reference F0.1 and Fmax values derived from a yield-per-recruit analysis. Based on the spawning stock-recruitment relationship, a stock recovery in the near future seemed unlikely because of low recruitment being expected from the extremely low spawning stock biomass in 1992–94. |
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