The Construction of Habitat Suitability Index Forecast Model of Ommastrephes bartramii Fishing Ground Based on Constrained Linear Regression

Abstract:

Neon flying squid (Ommastrephes bartramii) is an important commercial fishing target for China in Northwest Pacific. Accurate prediction of fishing grounds can improve the squid production capacity. The present study selected historical catch and fishing effort data of Chinese squid-jigging fishery from 2005 to 2013 as suitability index (SI) sources. SI curves were created through nonlinear regression based on 4 environmental factors, including sea surface temperature (SST), chlorophyll-a concentration (Chl-a), SST gradient (Grad) and the temperature of 100 m water layer (T100) from Argo float dataset. On the premise of given constrained conditions, two habitat suitability index (HSI) models were constructed based on catch and fishing effort. Non-significant explanatory variables in the model were eliminated via the stepwise regressions. By comparing the goodness-of-fit of two models, catch-based model provided higher accuracy than fishing effort-based one. The adjusted correlation coefficients were 0.853 (P<0.001), 0.773 (P<0.001), 0.789 (P<0.001), 0.745 (P<0.001) and 0.724 (P<0.0001) from July to November, respectively. The weight coefficients of SI for environmental factors were in accord with the constraint and seasonally varied. In particular, the SI of T100 played the most important role in the HSI score in the main fishing season (July, August and October) while the SI of SST was the major factor to affect HSI in November. The forecast experiment of HSI model was carried out with environmental factors in 2014. Spatial position of forecasted fishing grounds were consistent with actual ones, and catch in high HSI (>0.7) regions accounted for 49.06% of the total catch, while catch in low HSI (<0.3) regions accounted for only 9.06% of the total catch. These findings indicate that the HSI model is able to predict neon flying squid fishing grounds in Northwest Pacific.