Some Ecological and Biological Features of Giant and Popeye Grenadiers in the Pacific Waters off the Northern Kuril Islands and Southeastern Kamchatka
Alexei M. Orlov and Alexei M. Tokranov
Abstract.—The giant grenadier Albatrossia pectoralis and popeye grenadier Coryphaenoides cinereus are among the most abundant continental slope fish species of the North Pacific. Their high biomass constitutes about 2 million metric tons and they comprise a large portion of by-catch in deepwater bottom trawl and longline fisheries. However, these species are mostly discarded and their specialized fisheries are currently only in the initial stage. The ecology and biology of giant and popeye grenadiers in the Pacific off the northern Kuril Islands and southeastern Kamchatka are still poorly understood. This paper is based on results of studies conducted in 1992–2002 aboard Japanese trawlers in the Pacific waters off the northern Kuril Islands and southeastern Kamchatka. It describes seasonal changes of spatial and vertical distributions and bottom temperature preferences, provides data on their lengths and weights, length-weight relationships, sex ratios, and multi-annual, seasonal, and diurnal variations of catch rates. Relationships between mean body weight and capture depth are presented for different seasons. Data on composition of species co-occurring in catches are given for both grenadiers in respect to different times of year.