Comparisons of monthly and geographical variations in abundance and size composition of Pacific saury between the high-seas and coastal fishing grounds in the northwestern Pacific

Abstract

The monthly and geographical abundances and size compositions of Pacific saury were compared between the high-seas and coastal fishing grounds in the northwestern Pacific during 2000-2005 based on Taiwanese fishery data. The large-sized saury was dominant (44.3-71.4% of the catch) in the beginning of the fishing season, while the medium-sized saury followed and dominated from September to the end of the fishing season (70.1-92.4% of the catch). In the high seas, the total catch per unit effort (CPUE) (about 71.2% of the mean coastal value) and both the large-(about 55.0%) and medium-sized saury CPUEs (about 81.8%) were significantly smaller than those in the coastal waters. The mean proportions of the large-and medium-sized saury in the high-seas catch were about 86.6 and 107.0% of the coastal values, respectively. CPUEs for the total catch and the catch of medium-sized saury varied in a highly consistent way. The total and medium-sized CPUEs were negatively correlated with the sea-water temperature. When the temperature was held the same statistically, the total and medium-sized CPUEs were larger in the shoreward, southward, and shallower waters of the fishing grounds, while the large-sized CPUE was larger in the shoreward waters.

Predicting potential fishing zones for Pacific saury (Cololabis saira) with maximum entropy models and remotely sensed data

“…The occurrence of large-size Pacific saury (>29.0 cm in knob length) off the southern Kuril Islands during their spawning migration indicates that a high proportion of large-size Pacific saury moved from the high seas to coastal waters at the beginning of their migration toward the southwest-movement that was then followed by a similar migration of medium-size Pacific saury (24.0-29.0 cm in knob length). Therefore, abundance of Pacific saury off the coastal waters in our study is higher than the abundance observed in regions in the high seas (Huang, 2010). In addition, the high density of Pacific saury off Hokkaido and the Kuril Islands was probably related to the southward movement of the Oyashio Current (Tseng et al, 2011).…”

“…In addition, the high density of Pacific saury off Hokkaido and the Kuril Islands was probably related to the southward movement of the Oyashio Current (Tseng et al, 2011). The high presence of Pacific saury at the coasts also could be a result of a westward current intensification, which can result in the formation of oceanic fronts (Huang, 2010). These frontal features have been known as the preferred migratory routes of Pacific saury and other marine species (Saitoh et al, 1986;Zainuddin et al, 2008).…”

“…Most studies of Pacific saury have concentrated on distribution and migration and have used in situ or logbook data (Huang et al, 2007;Tseng et al, 2013), and models have been developed to investigate growth and abundance (Tian et al, 2004;Ito et al, 2004Ito et al, , 2007Mukaietal., 2007). In contrast, Watanabe et al (2006) proposed a spatial and temporal migration model for stock size that was dependent on SST.…”

Geographical variation in spawning histories of age-1 Pacific saury Cololabis saira in the North Pacific Ocean during June and July

“…Prior to 2000, the catch by Japan accounted for more than 80% of the total world catch, but this has since dropped to approximately 30% given increased recent foreign catches, concomitant with an expansion of fishing grounds and periods. Japanese and Russian fishing vessels mainly catch Pacific saury in their exclusive economic zone from August to December, whereas Taiwanese, Chinese and Korean fishing vessels operate in more eastern areas, mainly in the high seas west of 165°E from June to December (Huang et al 2007;Huang 2010;Tseng et al 2013Tseng et al , 2014.…”

A Comprehensive Monitoring and Assessment System for Multiple Fisheries Resources in the Northwest Pacific Based on Satellite Remote Sensing Technology

“…These results for squid fisheries were consistent with optimal SST requirements for neon flying squid at different life history stages (Chen et al, 2007;Alabia et al, 2015;Yu et al, 2020). Conversely, as the Pacific saury is a cold-water pelagic fish (Sugisaki and Kurita, 2004), the distribution of the saury vessels in summer was different from those of mackerel and squid vessels and mainly occurred in colder waters with SSTs ranging from 8 to 12 • C. Saury vessels were mainly concentrated in waters with SSTs between 15 and 18 • C starting in August, corresponding with the most suitable environmental factor (15 • C SST) affecting the distribution of saury during their southward-spawning migration in autumn (Huang, 2009).…”