Are deepwater fisheries sustainable? — the example of orange roughy ( Hoplostethus atlanticus) in New Zealand

Abstract

The deepsea environment is generally regarded as being one of low energy and productivity. Species exploited at depths of over 600 m like orange roughy ( Hoplostethus atlanticus), oreos (e.g. Allocyttus niger, Pseudocyttus maculatus), and macrourid rattails (e.g. Coryphaenoides rupestris, Macrourus berglax) have slow growth rates and high longevity compared to traditional commercial species from the continental shelf. They have low levels of sustainable yields, are vulnerable to overfishing, and have slow recovery rates. Yet, they are often high-value species, and this has maintained interest in developing new fisheries for deepwater species. In New Zealand waters orange roughy has been fished for 20 years. Familiar patterns of rapid fishery development with large catches, followed by contractions in stock distribution, and reductions in catch levels as the stocks become over-exploited, have occurred. Quotas in a number of New Zealand fisheries were reduced in the early 1990s, and this enables an insight into how stocks respond with reduced levels of exploitation, and how resilient and sustainable these fisheries may be in the long term. Examples are given for several New Zealand and Australian orange roughy fisheries. Changes in abundance, fishery performance, and biological characteristics are examined. In some cases fish stocks appear to be holding their own, and are supporting relatively stable catch rates, but in others stocks are still declining. There are few signs of biological compensation, and recruitment levels appear to be low. Lack of good data on levels and patterns of recruitment is a major source of uncertainty in current stock assessments, and a principal concern for long term sustainability of such fisheries