Modelling the effects of climate variability on habitat suitability of jumbo flying squid, Dosidicus gigas, in the Southeast Pacific Ocean off Peru

The jumbo flying squid Dosidicus gigas is a highly migratory species distributed throughout the Eastern Pacific Ocean. An integrated habitat suitability index (HSI) model was developed to evaluate the effects of climate variability (i.e. El Nino-Southern Oscillation) on the habitat suitability for D. gigas in the Southeast Pacific Ocean off Peru. The data used in the analysis included catch and fishing effort from the Chinese squid-jigging fishery over 2006-2013, as well as remotely sensed environmental data including sea surface temperature, chlorophyll a and sea surface height anomaly. Arithmetic mean HSI model was shown to have a better predictive performance and used to predict the HSI values and identify the suitable habitat for D. gigas over 2006-2012. Fishery and environmental data in 2013 was used to validate the model. The latitudinal location of suitable habitat was found to be important in determining the distribution of fishing efforts. Cross-correlation plot exhibited a significantly negative relationship between the average HSI values on the fishing ground and the Nino 3.4 indices with time-lags from 21 to 3 months, implying that the squid habitat responded quickly to the climate variability. Both suitable habitat areas and catches of D. gigas increased in La Nina periods and decreased in El Nino periods. The La Nina conditions tended to strengthen upwelling coupled with cool and nutrient-enhanced waters, which yielded favourable habitat conditions and high catches; whereas the El Nino conditions weakened upwelling coupled with warm and nutrient-depleted waters, which were unfavourable for squid habitat and reduced catches. Our findings indicated that large-scale climate variabilities could have great effects on squid habitat and such variabilities could be quantified by climate indices such as Oceanic Nino index.