Abundance prediction and influence of environmental parameter in the abundance of Octopus (Octopus vulgaris Cuvier, 1797) in the Gulf of Cadiz

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Inglés. Understanding the processes that influence octopus abundance is important in order to manage the fishinggrounds and offer advice on the exploitation of this important resource. Fluctuations in abundance of exploitedstocks may be due to a great variety of factors. However, in short-lived animals such as cephalopods, in whichabundance depends on strength of the recruitment, it is well known that population abundance is highly influenced by the environmental conditions.In this study we investigated the relationship between octopus (Octopus vulgaris) catches from the fisherylocated in the area off the Gulf of Cadiz (Spanish South Atlantic Region) and several hydrographic and oceanographic parameters such as sea surface temperature, surface chlorophyll-a, inorganic surface turbidity andclimatic indicators such as the NAO index, rain, WeMoi Index, AMO index and or Guadalquivir River discharges.In addition, a recruitment index was obtained from fishery-independent surveys, which was also used to investigate its effect on annual catches. Results revealed that abundance of octopus showed a significant negativerelationship with rain in the previous year as well as a positive effect of the recruitment index.We have obtained a model using the rain and the recruit index to forecast the catches.This model explained a high percentage of variation in annual catches and was used to forecast the next year’scatch providing results within the expected confidence intervals. This represents a potentially useful tool toguide fishery managers since no assessment of the species is currently conducted in the area.