Ichthyofauna on three seamounts off southern and central California, USA

Abstract

In many regions of the world, commercial fisheries for seamount-aggregating species have collapsed. Most are trawl fisheries, which have been implicated in the destruction and loss of fragile coral and sponge habitat and potentially endemic seamount species. Even with the intense fishing effort over seamounts, our understanding of processes regulating the distribution and abundance of seamount fish assemblages, which is vital to conservation policy, is weak. Here, we describe the abundance and distribution of demersal fishes found on 3 seamounts off central and southern California. Video observations were taken during 27 dives of a remotely operated vehicle (ROV), and were annotated in detail using the Monterey Bay Aquarium Research Institute's (MBARI) Video Annotation Reference System (VARS). Video analysis yielded 2151 observations of 36 identified taxa. No aggregations of fishes were observed during the surveys. Video transects were analyzed to quantify organism density. Similarity among seamounts was compared using Bray-Curtis similarity estimates. Our results indicate high similarity among seamount faunas at similar depths, a shift from provincial to abyssal/cosmopolitan species with increased depth, and no evidence of seamount endemism. KEY WORDS: Seamount fishes · Seamount biology · California seamounts · Deep sea fishes · Seamount ecology · Deep sea ecology Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 389: [223][224][225][226][227][228][229][230][231][232] 2009 (Wilson & Kaufmann 1987, Tracey et al. 2004, Hoff & Stevens 2005 or cosmopolitan (Wilson & Kaufmann 1987) faunas. Koslow (1997) demonstrated that seamount-aggregating fishes differ from background deep-sea fishes in both lifestyle and metabolism, suggesting that seamount fish faunas are in fact unique. These faunas, like other deep-sea fishes, are often composed of long-lived species with slow rates of reproduction and are, therefore, vulnerable to overfishing (Koslow 1997, Koslow et al. 2001, Froese & Sampang 2004, McClatchie & Coombs 2005. Seamounts are hypothesized to be able to support unique faunas for various reasons, including concentration of food and increased productivity (Genin et al. 1988, Rogers 1994. Of seamount fishes globally, macrourids, scorpaenids, morids, squalids, alepocephalids, and serranids are reported to be the most diverse families (Wilson & Kaufmann 1987), while scorpaenids, morids, serranids, macrourids, and squalids are the most abundant. Wilson & Kaufmann (1987) estimated that 11.6% of seamount fishes are endemic to seamounts, but also stated that most reports of endemism appear to be overestimated because of poorly known species distributions. This is supported by the increase in the known range of many species, including invertebrates, subsequent to their initial description (Tracey et al. 2004, Hall-Spencer et al. 2007, McClain 2007, O'Hara 2007, McClain et al. 2009).More recent studies suggest that seamount fish faunas are not unique to seamounts bu...

Assemblage structure is related to slope and depth on a deep offshore Pacific seamount chain

“…Indeed, corals were generally observed in low abundance at Taney Seamounts when compared with shallower and nearshore seamounts off California (Lundsten et al . ,b; McClain et al . , ).…”

“…However, the contribution of seamounts to total global biodiversity and many hypotheses regarding the processes maintaining seamount biodiversity remain to be determined (McClain ; Lundsten et al . ,b; Clark et al . ; Rowden et al .…”

First North Pacific records of the pointy nosed blue chimaera, Hydrolagus cf. trolli (Chondrichthyes: Chimaeriformes: Chimaeridae)

“…2a) was the first observation of these unknown bluish Hydrolagus specimens in the Northern Hemisphere, and the first of four observations from Monterey Bay, California. Specimen from trawl T-0142 was first reported by Lundsten et al 2009, and recorded off the coast of central California at the Davidson Seamount on 9 May 2000 at approximately 2064 m. A similar specimen was observed near the same location on dive T-1102 (Fig. 2b) at the Davidson Seamount, on 20 June 2007, at approximately 1641 m. Both specimens from dives T-0142 and T-1102 have striking similarities including: a short, pointed snout, with preopercular and oral canals that share a common branch from the infraorbital canal, bluish-grey body coloration, a concave first dorsal fin with keeled spine, large, triangular pectoral fins, and broad pelvic fins.…”

“…Hydrolagus colliei is found from Alaska to Costa Rica, while H. melanophasma occurs off southern California, USA to northern Chile (Angulo et al, 2014;Aguirre-Villaseñor et al 2013). However, a third species of Hydrolagus, first noted but not identified by Ebert (2003), had been observed by remotely operated vehicle (ROV) at Davidson Seamount off central California at a depth greater than 2000 m. Lundsten et al 2009 identify Hydrolagus trolli from the Davidson Seamount, however provide no descriptive information. Central North Pacific records of chimaeras are few, with only the purple chimaera, Hydrolagus purpurescens (Gilbert 1905), being reported from the Hawaiian Islands.…”

Spotlight: Davidson Seamount

“…Large corals occur in dense aggregations on local peaks and adjacent steep slopes, but are less abundant in valleys or on the flanks. Researchers have found little evidence of species endemism on and around this seamount (Lundsten et al 2009a(Lundsten et al , 2009bMcClain et al, 2009). Animals are, however, found in greater abundance, biomass, and better health than those found in less-optimal habitat, suggesting that seamounts may be a source, rather than a sink, for some species (McClain et al, 2009 …”