Recomendación de capturas biológicamente aceptables de anchoíta patagónica (Engraulis anchoita, 41º S-48º S) durante 2012
Advise on Biologically Allowable Catch (BAC) for Southern Argentine anchovy (Engraulis anchoita, 41° S-48° S) during 2012. To assess the evolution since 1990 and the current status of Argentine anchovy Southern stock, an Age Structured Population Model (ASPM) was used. Modeling of catches according to a four-month period pulses allowed to predict annual yields so as to get them close to the nominal catches officially recorded. Some independent indexes of stock abundance (eight acoustic estimates of total biomass and five estimates of spawning stock biomass obtained with the Daily Egg Production Method) and the proportion of individuals per age group assessed during the same cruises were used to calibrate the fitting. No stock-recruitment function but a mean recruitment allowing for some annual deviations was estimated. The model was implemented through an AD Model Builder code. According to the year, stock abundance during the reproductive season ranged 1.0-2.2 million tons, with an average of 1.36 million. The theoretic mean recruitment was estimated at 140,640 million fish (C.V. = 14.6%). The annual fishing mortality rate, averaging 0.006, reflected the low exploitation level of the resource. Biological Reference Points (RP) based on a spawning stock biomass per recruit (SSB/R) analysis were determined as F66 = 0.70 and F40 = 2.2. The spawning stock biomass SSB66 = 468,000 t would represent the Target Reference Point for the stock, with the Limit RP calculated at 287,000 t, and the current SSB (December 2011) at 711,800 t. The estimate of total stock biomass at the beginning of the last year of actual fishing was 1,470,400 t (standard deviation = 507,480 t). Said parameters were used as starting values to evaluate the future status of the stock under different, increasing values of fishing mortality and to perform a risk analysis. If the Harvest Control Rule proposed in this paper was observed, the BAC for southern anchovy could be represented by the 226,000 t predicted for the 2012 F66 rate that would imply, besides, a low risk of decrease of spawning stock biomass below the SSB40 limit level. Nevertheless, the proportion of juvenile anchovies in catches would increase sharply. For that reason and the uncertainty about estimates arising from the lack of recent direct estimates and the low current exploitation of the stock, as advised in previous years and officially established, a Total Allowable Catch of 100,000 t for 2012 is suggested.
| Main Authors: | , , |
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| Format: | Journal Contribution biblioteca |
| Language: | Spanish / Castilian |
| Published: |
2013
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| Subjects: | Stock assessment, Yield, Statistical models, Age composition, Clupeoid fisheries, |
| Online Access: | http://hdl.handle.net/1834/5508 |
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