Investigating priceless orange roughy (Hoplostethus atlanticus) population dynamics using linear models of catch per unit effort (CPUE)
Degree GrantorUniversity of Canterbury
Degree NameMaster of Science
Who do you trust when trying to make an informed and environmentally friendly choice on fish fillets at the supermarket? The Marine Stewardship Council and Forest and Bird have contradictory opinions when it comes to orange roughy (Hoplostethus atlanticus) sustainability. The controversy ultimately comes down to the fact that orange roughy is a deep sea species and while management may have been successful for inshore species, the vast number of unknowns relating to deep sea stocks and the ecosystem effects of deep sea fishing mean that what initially seemed like sustainable management repeatedly resulted in disastrous consequences. The collapse of some of the early orange roughy stocks is proof of this. The question is, have we learnt enough from those early failures to avoid repeating those mistakes, or is it only a matter of time before the next crash of one of our deep sea fisheries? Fitting a selection of linear models to catch per unit effort (CPUE) data, corresponding to orange roughy catch from the Priceless region in the Sub-Antarctic, led to the discovery of significant seasonal patterns and an annual linear trend in CPUE with a breakpoint in 2004. The assumed relationship between CPUE and abundance is difficult to quantify but the cessation of fishing in the region leads to the conclusion that decreases in CPUE correspond to decreases in orange roughy abundance.