ABSTRACT
With survey data from three voyages in the summer of 2014, 2016, and 2017, spatial distribution and inter-annual variability of spawning grounds of Cynoglossus joyneri in the coastal waters of Yellow Sea were examined based on Tweedie-generalized additive model (GAM). The results showed that the spawning grounds of C. joyneri mainly distributed in the Haizhou Bay ranging within 34°00'-35°18' N, 119°30'-121°30' E. The other one in Subei Shoal 32°18'-34°00' N, 120°18'-122°00' E. Fish eggs of C. joyneri were few in the southern waters of Shandong Peninsula 34°42'-36°48' N, 119°30'-122°00' E. The distribution of fish eggs was significantly related to the location (i.e., longitude and latitude), depth, and sea surface temperature, and did not relate to the sea surface salinity and surface chlorophyll a. The optimal range of depth, sea surface temperature, sea surface salinity, and surface chlorophyll a were 15-26 m, 29-32 â, 22-25 and 0.10-3 mg·m-3, respectively. There was notable inter-annual variability in the spatial distribution of spawning grounds of C. joyneri and its influencing factors. Overall, the distribution of spawning grounds is relatively stable, but potentially move northward in the year with high sea surface temperature.
Subject(s)
Chlorophyll A , Fishes , Animals , Salinity , Seasons , TemperatureABSTRACT
Japanese Spanish mackerel (Scomberomorus niphonius) is one of the main economic fish species in the Yellow Sea. To understand its spawning habitat and population dynamics in the early stage, we examined the distribution and environmental characteristics of spawning ground of Japanese Spanish mackerel using their egg survey data collecting in 2015 (late May) and 2017 (late May) in the coastal waters of Yellow Sea. The generalized additive model (GAM) with the Tweedie distribution was used to analyze the distribution and environmental characteristics of its spawning ground. The results showed that egg distribution was significantly related to the location (i.e., latitude and longitude), water depth, and sea surface temperature (SST), but not related to sea surface salinity (SSS). The optimal range of depth and SST were 15-30 m and 16-20 â, respectively. The mackerel spawning ground mainly distributed in the region Shidao fishing ground (area near 36°30' N,121°48' E) and Haizhou Bay (33°30'-36° N,119°30'-121°30' E). There were some clear inter-annual differences in the distribution of mackerel spawning ground, with the spawning ground tending to northward in the year with higher sea temperature. Therefore, it is necessary to manage and protect the above spawning ground (especially the Haizhou Bay), establishing the corresponding ecological protection and restoration strategy, to realize sustainable exploitation of mackerel fisheries resources in the Yellow Sea.
Subject(s)
Perciformes , Animals , China , Ecosystem , Fisheries , Population DynamicsABSTRACT
Stow net fishery is one of the important fishing methods in southern Yellow Sea. Based on the 2006-2009 data from the stow net fishery resources survey in the southern Yellow Sea in spring, and by using the generalized linear model (GLM) and generalized additive model (GAM), this paper quantitatively analyzed the relationships between the catch distribution of Pseudosciaena polyactis and Lophius litulon and the environmental factors such as year, position, water depth, and sea surface temperature (SST). Compared with GLM model, GAM model could better explain the relationships between the spatiotemporal distribution of the catch per unit effort (CPUE) of P. polyactis and P. litulon and the environmental factors. There was a significant negative correlation between the CPUE of the two fish species. The P. polyactis' CPUE showed a decreasing trend from north to south along the latitude direction, being smaller especially around the Yangtze River estuary, and the L. litulon' s CPUE was also smaller near the Yangtze River estuary. The CPUE of the two species showed a significant correlation with the SST. The calculated optimal scale of the SST for L. polyactis and P. litulon was 9-11 degrees C and 9-14 degrees C, respectively.
