Assessing of a portion of the Pacific Thunnus albacares stock: Ahi in the Main Hawaiian Islands

TL;DR

This paper introduces a new modeling approach linking local Hawaiian yellowfin tuna stock dynamics to the larger Pacific stock, demonstrating the local stock is not overfished and fisheries are sustainable.

Contribution

A novel state-space logistic production model connects local and Pacific-wide tuna stocks using historical catch data and abundance indices.

Findings

Local stock is not overfished

Fisheries are fishing at acceptable levels

Model demonstrates feasibility of linking local and Pacific stocks

Abstract

Regional tuna fishery management organizations cannot provide specific advice to local fishery managers in small island jurisdictions. The State of Hawaii maintains time series of yellowfin tuna catches dating back to 1949, but these data have never been formally applied to evaluating the effects of the yellowfin fishery in the Main Hawaiian Islands on the local stock. I develop a new approach utilizing these data that links the local stock dynamics to the dynamics of the larger Pacific stock. This approach uses a state-space logistic production model linked to the larger Pacific stock using an index of abundance. The conclusion is that such a model is feasible, that the local stock is not overfished and that local fisheries are fishing at acceptable levels.