Larval feeding habits of Diaphus theta, Protomyctophum thompsoni, and Tarletonbeania taylori (Pisces: Myctophidae) in the transition region of the western North Pacific

Abstract

We examined the larval feeding habits of the 3 dominant myctophids, Diaphus theta, Protomyctophum thompsoni, and Tarletonbeania taylori, in the transition region of the western North Pacific. Feeding incidence for D. theta and T. taylori larvae was higher during the day than at night (mean: 70.7 to 84.4% vs. 2.2 to 4.1%), indicating that they are daytime visual feeders. Larvae of P. thompsoni were also visual feeders, with a daytime feeding incidence of 83.0%. The proportion of nighttime feeding in P. thompsoni gradually increased with development, which suggests faster larval adaptation of this non-migrant species to the poor light conditions in the mesopelagic zone. D. theta larvae ≤7.9 mm in body length (BL) fed mainly on copepod nauplii, which were replaced by calanoid copepodites and Oithona spp. in larvae ≥8.0 mm BL. The most important prey for smaller P. thompsoni and T. taylori larvae ≤7.9 mm BL were nauplii and Oithona spp., which were replaced by calanoid copepodites and ostracods in P. thompsoni and copepod eggs in T. taylori with increased development. Competition for prey among the larvae of these 3 myctophids was mostly avoided because of diet and habitat-depth segregation. Interspecific comparisons of feeding habits among the 3 species, in addition to larvae of 3 other myctophids found in the study area, suggested that their feeding strategies were associated with mouth size, i.e. larvae with larger mouths tended to take larger prey rather than a large number of smaller prey. This interspecific difference in feeding strategy is reflected in the diverse morphological characters of myctophid fish larvae.

Trophic ecology of three dominant myctophid species in the northern California Current region

“…The fish consumed by T. crenularis was tentatively identified as Lipolagus ochotensis, a common midwater bathylagid found off Oregon. It is relatively well established that trophic competition in myctophid communities can be significantly reduced through both inter-and intraspecific resource partitioning (Hopkins & Gartner 1992, Gartner et al 1997, and recent reports have indicated differential feeding patterns in lanternfish larvae as well (Conley & Hopkins 2004, Sassa & Kawaguchi 2005.…”

“…The fish consumed by T. crenularis was tentatively identified as Lipolagus ochotensis, a common midwater bathylagid found off Oregon. It is relatively well established that trophic competition in myctophid communities can be significantly reduced through both inter-and intraspecific resource partitioning (Hopkins & Gartner 1992, Gartner et al 1997, and recent reports have indicated differential feeding patterns in lanternfish larvae as well (Conley & Hopkins 2004, Sassa & Kawaguchi 2005.In our study, the most common and abundant euphausiid in oceanic waters off Oregon, Euphausia pacifica, was by far the most important prey for all 3 species based on IRI val-91 June August September p T. crenularis SCI (% BW) 3.7 ± 3.4 2.5 ± 2.9 1.9 ± 2.2 < 0.0005 No. of prey items per stomach 12.1 ± 17.5 25.1 ± 46.4 10.5 ± 13.0 < 0.005 No.…”

Late winter larval fish assemblage in the southern East China Sea, with emphasis on spatial relations between mesopelagic and commercial pelagic fish larvae

“…This would potentially lead to the intra-and interspecific competition for food resources among the larval fish in the food poor Kuroshio waters. Various patterns of habitat depth and feeding would possibly reduce the competition for the limited food resources in the Kuroshio waters (Watanabe et al, 2002;Sassa et al, 2002Sassa et al, , 2004aSassa and Kawaguchi, 2005), as suggested in the oligotrophic subtropical-tropical waters of various parts of the world oceans (e.g. Sabatés and Saiz, 2000;Sabatés et al, 2003;Conley and Hopkins, 2004).…”

Biomass fluctuation of two dominant lanternfish Diaphus garmani and D. chrysorhynchus with environmental changes in the East China Sea

“…Although mesopelagic fish are not generally fished commercially, they represent a substantial biomass in oceanic waters and are a critical but poorly understood intermediate trophic link between the mesozooplankton and higher trophic levels including fishes, seabirds, and marine mammals [1][2][3][4][5]. Lanternfish (Diaphus spp.)…”