Hoki Fishery Research Articles

Unreported bycatch in the New Zealand West Coast South Island hoki fishery

Abstract There are recognised benefits to managing fisheries by individual transferable quotas (ITQs), but ITQs may increase incentives to discard fish. Trawl data from government-observed trawlers in the New Zealand hoki fishery were used to predict catches of unobserved vessels. These predictions were compared with the catches unobserved vessels reported. Unobserved vessels’ reported catches were significantly different to observed vessels’ catches. There was clear evidence of misreporting in the hoki fishery. Misreporting deprives stakeholders of rentals, distorts catch statistics, and threatens the integrity of ITQ systems. If reporting is similarly biased in other fisheries, the issue cannot be safely ignored.

Westland Petrels and the Hoki fishery: determining co-occurrence using satellite telemetry

It has been assumed that Westland Petrels, Procellaria westlandica, feed extensively on fisheries waste and this habit has been considered at least partly responsible for an increase in the Westland Petrel population. However, no studies have tested this assumption. In this study, 12 Westland Petrels were tracked by satellite for a total of 22 foraging trips. The birds’ tracks were compared with the distribution of Hoki, Macruronus novaezelandiae, fishing vessels, predominantly deep-sea trawlers, and the proportion of time that they spent in the vicinity of fishing vessels was assessed. This satellite tracking study was complemented by diet sampling and a survey of Westland Petrels at sea in a wider study of the importance of fisheries waste in the diet of Westland Petrels.There was considerable variation in the amount of time that Westland Petrels spent in the vicinity (i.e. within 5 km) of Hoki fishing vessels. The mean length of foraging trips of satellite-tracked birds was 4.1 days. On average, tracked birds spent one third of a foraging trip in the vicinity of vessels. Some birds spent most of a foraging trip near the fishing fleet, while others spent very little time near vessels. While near fishing vessels, flight speeds considerably lower than those attained away from fishing vessels suggested that the birds were scavenging there.In 68% of tracked flights, birds apparently stopped at or near the fishing fleet during the 12 h before their return to the colony. Because of this, it is likely that diet studies undertaken in conjunction with satellite tracking overestimated the importance of fisheries waste.The amount of time that birds spent outside the Hoki fishing areas shows that, despite the large-scale fishery, Westland Petrels continue to forage over much wider areas than those occupied by the Hoki fishing fleets.

Analysis of vessel movements and strategies using commercial catch and effort data from the New Zealand hoki fishery

Analysis of vessel movements and strategies using commercial catch and effort data from the New Zealand hoki fishery

Analysis of spatial structure in fish distribution using commercial catch and effort data from the New Zealand hoki fishery

A linear model was fitted to commercial catch per unit effort data in the spawning hoki trawl fishery off the west coast of the South Island of New Zealand. Correlations in the residuals from this model extend out to 11 nautical miles and persist for periods of up to 14 days, suggesting that there is patchiness in the fish distribution on this spatial and temporal scale. Simulation studies show that this method can detect patchiness in the density distribution even when the trawl shots are comparable in length with the size of the patches, and that the extent of the correlations correctly estimates the size of the patches. Resume : Un modle linOaire a OtO adaptO aux donnOes de prises commerciales par unitO dieffort liOes ‡ la pŒche au chalut de hokis reproducteurs sur la cUte ouest de liOle sud, Nouvelle-ZOlande. Les corrOlations dans les rOsidus de ce modle siobservent sur une distance de 11 milles marins et durant une pOriode pouvant atteindre 14 jours, ce qui porte ‡ croire que la distribution des poissons sur cette Ochelle spatio-temporelle est irrOgulire. Des Otudes de simulation rOvlent que cette mOthode permet de dOtecter liirrOgularitO de la distribution de la densitO mŒme lorsque la longueur des traits de chalut correspond ‡ celle des taches et que liOtendue des corrOlations permet diestimer correctement la taille des taches. (Traduit par la ROdaction)

Analysis of vessel movements and strategies using commercial catch and effort data from the New Zealand hoki fishery

On a examine des valeurs normalisees de taux de capture obtenues au moyen d'un modele multiplicatif des prises de peche commerciale par unite d'effort dans le cadre de l'etude des deplacements et des strategies d'un bateau de peche. On a fait une transformation logarithmique des prises par unite d'effort effectuees dans une peche commerciale au chalut du hoki en fraye, au large de la cote occidentale de l'ile South, en Nouvelle-Zelande; on a ensuite ajuste un modele lineaire aux donnees transformees. Les valeurs residuelles obtenues au moyen de ce modele ont ensuite ete examinees; les taux de capture resultant de traits de chalut effectues par differents bateaux a differents moments de la journee ont ete normalises, si bien qu'ils sont comparables. Les decisions relatives au lieu de peche seraient fondees tant sur les antecedents de capture recents du bateau que sur les observations relatives au lieu de peche et au regroupement des autres bateaux. Rien n'indique que le transfert d'information soit suffisant pour que les decisions soient fondees sur le taux de capture des autres bateaux de la flottille.

Analysis of spatial structure in fish distribution using commercial catch and effort data from the New Zealand hoki fishery

Analysis of spatial structure in fish distribution using commercial catch and effort data from the New Zealand hoki fishery

Net damage injuries to New Zealand hoki,Macruronus novaezelandiae

Abstract The occurrence of trauma, consistent with healing net damage, was observed in 1988 from the New Zealand west coast hoki fishery, where hoki (Macruronus novaezelandiae), hake (Merluccius australis), silver warehou (Seriolella punctata), rays bream (Brama brama), and frostfish (Lepidopus caudatus) were affected. In 1989 and 1990 similar trauma was observed on hoki from the New Zealand Southern Plateau. Data on prevalence of cuts, scrapes, and scars are provided for the Southern Plateau. In some of the tows recorded from the Southern Plateau, over 5% of the fish caught had previous encounters with nets.