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Spatiotemporal catch patterns and population distributions of bigeye Pacific opah (Lampris megalopsis) and smalleye Pacific opah (L. incognitus) in the eastern North Pacific Ocean
Get PDF—Opah (Lampris spp.) are commercially valuable, non-target fish that are regularly landed in pelagic longline fisheries in the central and eastern North Pacific Ocean. Genetic studies have confirmed 2 species in the region: bigeye Pacific opah (L. megalop-sis) and smalleye Pacific opah (L. incog-nitus). Spatial distributions of each species are not well-defined, and little is known about species-specific catch distributions because the 2 species are difficult to distinguish visually. The objectives of this study were to charac-terize spatiotemporal patterns of opah landings by using catch per unit of effort (CPUE) from logbook and observer data, for the period 1995–2018, and genetics-based species identifications. Results from generalized additive models indi-cate that bigeye Pacific opah dominate west of 140°W and that smalleye Pacific opah dominate waters east of 130°W (dominance is defined as a proportion of catch ≥0.7). The deep-set pelagic longline fishery had higher opah CPUE than the shallow-set fishery across the geographic range of these fisheries. Opah CPUE increased from west to east on both longline gears, indicating higher overall opah CPUE in the eastern regions of both fisheries, primarily dominated by smalleye Pacific opah. Opah CPUE also increased over time as the Hawaii-based longline fisheries expanded eastward. The results of this study highlight the need for species-specific catch data and will inform management of opah species
Opah and king-of-the-salmon hematocrit data (Table S1)
No full textOpah and king-of-the-salmon hematocrit data (Table S1
Opah and king-of-the-salmon ventricular mass (Table S1)
No full textOpah and king-of-the-salmon ventricular mass (Table S1
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Characterizing patterns of opah (Lampris spp.) catch-per-unit-effort in the eastern North Pacific Ocean
Get PDFThis project examines opah catch in the North Pacific. The goal is to visually characterize temporal and spatial patterns in fishing effort, catch, and aggregate nominal catch-per-unit-effort (CPUE) for the Hawaii and California based deep-set pelagic longline fishery to see if it is possible to differentiate the spatial distributions of both opah species known to be in the North Pacific. It should be noted that the two species are not differentiated in the data and are recorded simply as generic “opah”. To examine patterns, analyses were performed using logbook data from 1996 to 2018 to summarize catch and effort information into 5O x 5O spatial blocks to form a grid across the fishery range. Average annual number of sets, catch, and aggregate nominal CPUE were visualized for the entire time series. The fishery has expanded significantly over the last 23 years from just around the Hawaiian Islands to encompassing most of the ocean between Hawaii and continental North America, outside the U.S. exclusive economic zone. Opah CPUE is highest in the northeastern extent of the fishery range, east of 150O W, with catch and CPUE steadily increasing from west to east. Prior DNA studies indicate that most smalleye opah (Lampris incognitus) are found near the California coastline and most bigeye opah (Lampris megalopsis) are found near Hawaii, which suggests that the North Pacific areas with high opah CPUE are likely dominated by smalleye opah
Opah dive profile and temp measurements (Fig. 1)
No full textOpah dive profile and temp measurements (Fig. 1
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