Comments about the relationship between temperature and giant squid catches

Abstract

ResumenLa pesquería de calamar gigante (Dosidicus gigas D'Orbigny, 1835) es un recurso inestable que ha mostrado amplias variaciones en abundancia y disponibilidad en los últimos 20 años, las cuales se intentaron explicar mediante una hipótesis que relacionaba los efectos de El Niño y la temperatura del mar sobre la pesquería. Recientemente, con datos de cruceros de investigación se ha retomado la hipótesis que supone que la temperatura del agua es un factor que incide en el desplazamiento del calamar, de tal forma, que las capturas se pueden relacionar con la temperatura media en las zonas de pesca, estableciendo la validez de la hipótesis con datos de abundancia relativa (AR) de un crucero de investigación que se reconocen como altamente desviados. De esta forma, la precisión en la relación captura-ambiente, del calamar gigante, está determinada por dos factores: (a) la correcta estimación del índice de AR del recurso, el cual debe ser corregido con un estimador insesgado de varianza mínima, bajo una distribución lognormal, lo que permite trabajar toda la serie de datos sin descartar información; y (b) la relación funcional de AR con la temperatura, que debe ser no paramétrica, evitando así la autocorrelación entre las mediciones de temperatura y, por consiguiente, reconocer que la relación entre la temperatura y las capturas de calamar no es directa (lineal), comprendiendo de esta forma que el efecto de la temperatura del mar sobre el índice de AR de calamar es totalmente aleatorio, ya que en la AR existe un error de observación que debe ser evaluado.Palabras clave: Dosidicus gigas, índice de abundancia, error de observación. AbstractThe fishery of the giant squid (Dosidicus gigas D'Orbigny, 1835) is an unstable resource that has shown wide variations in its abundance and availability in the last 20 years, which were tried to be explained by a hypothesis that related the effects of El Niño and the sea temperature on the fishery. Recently, with data obtained in research surveys, the hypothesis that water temperature is a factor that affects the displacement of the squid has been considered again, in such a way that catches can be related to the average temperature in the fishing zones, validating the hypothesis with relative abundance data (AR), obtained in a research survey, which are known to be highly skewed. In this way, the accuracy in the catch-environment relationship of the giant squid is determined by two factors: (a) the correct estimation of the resource's AR index, which must be corrected with an unbiased estimator of minimum variance, under a lognormal distribution, what allows working data series without discarding information; and (b) the functional relationship of AR with temperature and therefore, recognizing that the relationship between temperature and squid catches is not direct (linear), thus understanding that the effect of the sea temperature on the squid's AR index is random, since in the AR there is an observation error that must be evaluated.

EFFECT OF REFRIGERATED STORAGE ON PROTEOLYTIC ACTIVITY AND PHYSICOCHEMICAL AND MICROSTRUCTURAL PROPERTIES OF GIANT SQUID (DOSIDICUS GIGAS) MANTLE MUSCLE

“…The giant squid ( Dosidicus gigas ) is a seafood resource found in abundance on the Pacific Coast of Mexico, mainly in the Gulf of California. Harvest varies considerably because of environmental factors such as “El Niño” (Morales‐Bojorquez 2002). Eighty percent of the total catch is exported as raw material to the food industry in Korea, U.S.A. and Canada as reported by the Mexican Aquaculture and Fishing Committee (CONAPESCA 2003); the rest is merchandised frozen or under refrigeration on ice as a nonexpensive protein source (SAGARPA 2004).…”