Vulnerability of deepwater demersal fishes to commercial fishing: Evidence from a study around a tropical volcanic seamount in Papua New Guinea

• Published in: Fisheries research Vol. 81; no. 2; pp. 126 - 141
• Main Authors: Fry, G.C., Brewer, D.T., Venables, W.N.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.11.2006; Elsevier
• Subjects: Agnatha. Pisces; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Biomass; Dropline survey; Exploitation and management of natural biological resources (hunting, fishing and exploited populations survey, etc.); Fundamental and applied biological sciences. Psychology; Life history; Lihir Island group; Marine; Maximum sustainable yield; Multi-species; Papua New Guinea; Pisces; Tropical deepwater fishes; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Volcanic seamount; Papua New Guinea; Melanesia; Oceania; ISEW, Papua New Guinea; ISEW, Papua New Guinea, Bismark Archipelago, Lihir I; IS, Tropical Pacific; Life history; Papua New Guinea; Multi-species; Tropical deepwater fishes; Biomass; Volcanic seamount; Lihir Island group; Maximum sustainable yield; Dropline survey; Benthic organism; Vulnerability; Deep water; Fishing; Island; Vertebrata; Fishery; Pisces; Yield; Seamount
• ISSN: 0165-7836; 1872-6763
• DOI: 10.1016/j.fishres.2006.08.002

The deepwater fishes around the Lihir Island group, Papua New Guinea, were assessed for their vulnerability to exploitation from a potential commercial fishery. Three dropline surveys were made between 1999 and 2002 to estimate catch rates and life-history parameters. Growth parameters were obtained using the von Bertalanffy growth function fitted to length-at-age data from annuli counts in sectioned otoliths. Mean catch rates and total mortality rates were then used to estimate total fish biomass and maximum sustainable yields for the deepwater species around the island group. A total of 975 fish of 98 species were caught during 886 line hours of fishing. Most of these species are commercially valuable: 17 species are commonly fished commercially in other tropical Pacific regions. However around the Lihir Island group, their catch rates (1.38 ± 0.16 kg/line h) were lower and more variable than elsewhere in the Pacific, probably because of the limited deep-slope habitat. Total deepwater fish biomass between the 125 and 350 m depth zone was estimated at 17.4 metric tonnes with an annual sustainable yield of between 1213 and 3445 kg. In addition, many of the deepwater species may be long-lived, slow-growing species with low mortality rates. Our results suggest that the deepwater fish stock at the Lihir Island group is highly susceptible to overfishing at only moderate levels of fishing pressure. We therefore recommend that a precautionary approach should be taken, including accurate long-term monitoring of catches, if these stocks are to be commercially exploited.