What you can do with one deep-sea fish…
In the deep-sea there are many species for which there is limited amounts of biological information. It's safe to assume that if there's no money to be made from it, then there's not likely to be all that much in the way of research regarding it. In June 2014 I had the opportunity to dissect a banded bellowsfish that had come to us mixed up with one of the giant squids we were dissecting for a live webcast. It turns out that this is a species of deep-sea fish that not really all that much is known. I was able to look in both its stomach and intestines, describe what this particular fish had recently been eating, and make some comments regarding it's ecological role.
Figure one. A banded bellowsfish possibly feeding from the seabed off the Wairarapa coast in approx. 300–400 m (image courtesy of the Ministry for Primary Industries. The black bar indicates 20 cm).
A brief summary of current level of knowledge regarding banded bellowsfish
The banded bellowsfish (Centriscops humerosus (Richardson 1846)) is a small fish (to ~30 cm) with a circumglobal distribution in temperate waters of the southern hemisphere. Commonly encountered between depths of 300–600 m (Froese & Pauly 2014; Francis et al. 2002). In New Zealand waters it is found on the continental slope, with a preferred depth of ~460 m (Francis et al. 2002). Because it’s a small fish, that lives in quite deep-water, nobody really knows all that much about it.
However, banded bellowsfish have been reported as bycatch
in some New Zealand upper-slope fisheries, particularly those for hoki (Macruronus navaezealandiae Hector 1846)
and scampi (Metanephrops challengeri
Balss 1906) (Francis et al. 2002). Despite this, very little is known regarding their
ecology, especially in New Zealand waters.
Observations based on both still
(Fig. 1, 2) and video footage suggest that they swim in close proximity to the
bottom and are adverse to light (Pakhorukov and Parin 2012). Globally, little
is known of their feeding, although off Tasmania they were found to feed mainly
on brittle stars (Ophiuroidea) (Blaber & Bulman 1987). This feeding coupled with
their proximity to the bottom, suggests that they may feed from, or near the
seabed (benthic feeders). Incidentally, there are also anecdotal reports of banded
bellowsfish in captivity breaking the surface and shooting water out of their
mouths (Hannam pers. com.). This latter behaviour suggests that they might use
jets of water to disturb or expose prey from the seabed. Pakhorukov and Parin
(2012) also found that this species is more common around areas of
three-dimensional complexity, e.g., coral, sponges etc… It is well known that
in the deep-sea areas of increased structural complexity yield higher
species-richness, so this could suggest that they could be utilising these
areas for feeding or refuge.
Figure two. Two banded bellows fish swim in close proximity to the seabed, off the Wairarapa coast in approx. 300–400 m (image courtesy of the Ministry for Primary Industries. The black bar indicates 20 cm).
New data and conclusions
This is what I found: in the stomach there were three different valviferan isopods (a marine variety of slater). There was much more variety in prey in the intestinal contents; valviferan isopods, sections of sedentary worm tubes (and their remains), amphipod remains (a bit too digested to really tell much more), a nuculanid bivalve (clam), and a small (~3 mm) gastropod snail (?Rissoid-like). All these food items are consistent with a benthic-feeding mode.
One of the interesting things I've found looking in the stomachs and intestines of deep-sea fish is that they often contain different things, and often the same fish can have different items in their stomachs and intestines (a topic I will write more on in the future).
While this is interesting dietary information, I was only looking in one fish, and
it would be quite bad science to try and conclude too much from these data. However,
it is a diet that is consistent with what little data exists. and what it does
suggest is that there is an interesting project here for someone; not just
describing the trophic role of this species, but analysing it’s size and age
structure, as it’s probably safe to assume that this not been done.
References
Blaber SJM, Bulman CM 1987. Diets of fishesof the upper continental slope of eastern Tasmania: content, calorific values,dietary overlap and trophic relationships. Marine Biology 95: 245–356.
Francis MP, Hurst RJ, McArdle BH, Bagley
NW, Anderson OF 2002. New Zealand demersal fish assemblages. Environmental Biology of
Fishes 65: 215–234.
Froese RD, Pauly D. Editors.
2014. FishBase. World Wide Web electronic publication. http://www.fishbase.org, version (11/2014).
Pakhorukov NP, Parin NV 2012. Visual observations
of fish at the Whale Ridge (Atlantic Ocean) from the Sever-2 manned underwater vehicle. Journal of Ichthyology 52 (9): 579–591.
