Spatiotemporal variations in nutritional status and feeding habits of immature female bighand thornyhead Sebastolobus macrochir off the Pacific coast of northern Honshu, Japan

Abstract

Nutritional status and feeding habits of immature female bighand thornyhead Sebastolobus macrochir were assessed based on Fulton's condition factor K, hepatosomatic index (HSI), and stomach observations. Fish were obtained from bottom trawl samples taken seasonally during 2006/2007 in the Tohoku area, off the Pacific coast of northern Honshu, Japan. Results of the generalized linear model (GLM) indicated that fish condition deteriorated with depth, and small fish had a lower K, HSI, and percent stomach content index (SCI) than larger specimens. The empty stomach rate was higher in deeper waters in northern Tohoku (except for small fish from spring to autumn) and in southern Tohoku (spring/summer). Changes in the index of relative importance (%IRI) showed that the main prey items changed from nutritionally high to low prey items with depth. This suggests that deeper waters, where fish with the lowest condition values occur, are a poorer quality habitat for immature bighand thornyhead and that small fish are subordinate to larger fish. The effect on growth, due to variations in nutritional status and feeding habits, produced by the distributional changes in bighand thornyhead is also discussed.

Influences of Ocean Currents on the Diets of Demersal Fish Communities in the Western North Pacific Revealed by Their Muscle Carbon and Nitrogen Isotopic Compositions

“…The 14 C Bulk value of A. elongatus, the highest among those of other demersal fish, may be explained by its habitat preference for relatively shallow water (Kitagawa, 1990;Fujita et al, 1995) (catch-record depth: 20-269 m; Supplementary Table 1), which is mainly affected by 14 C-enriched DIC from the Tsugaru/Kuroshio Current. By contrast, the 14 C Bulk value of S. macrochir (-18.1 , n = 1), the lowest among those of other demersal fish, may reflect its feeding preference for benthic animals (Hattori et al, 2009b), which originate in 14 C-depleted DIC in deep waters.…”

Seasonal and spatial variations in prey utilization and condition of a piscivorous flatfish Paralichthys olivaceus

“…7) might also reflect the difference in prey availability, although no evidence for this was observed; SCI during this period was lower in the northern area. The importance of prey utilization for the condition of predatory fishes has also been suggested for other demersal fishes such as Greenland halibut Reinhardtius hippoglossoides (Román et al 2007), Atlantic cod Gadus morhua (Pardoe et al 2008), bighand thornyhead Sebastolobus macrochir (Hattori et al 2009), and grey gurnard Eutrigla gurnardus (Weinert et al 2010).…”

Diel feeding rhythms, daily ration, and seasonal changes thereof in marbled flounder Pseudopleuronectes yokohamae

“…The stomach content weight index (SCI) was used to standardize the stomach contents data: SCI = SCW × BW −1 × 100. To analyze variation in the SCI, we constructed a GLMM with Gaussian family and log‐link function, following Hattori, Okuda, Narimatsu, Ueda, and Ito () with some modifications: the response variable was [SCW + 0.00001], initial explanatory variables and random variable were same as those in the GLMM for empty stomach rates, and log (BW) was used as an offset term. Because the SCW involves zero data, we added a negligible value of 0.00001 to the SCW to allow logarithm transformation.…”

“…Gaussian family and log-link function, followingHattori, Okuda, Narimatsu, Ueda, and Ito (2009) with some modifications: the response variable was [SCW + 0.00001], initial explanatory variables and random variable were same as those in the GLMM for empty stomach rates, and log (BW) was used as an offset term.Because the SCW involves zero data, we added a negligible value of 0.00001 to the SCW to allow logarithm transformation. Thefinal model was selected based on the Akaike information criterion (AIC).…”