Click here to see Biologically sampled seamounts worldwide. (Stocks 2004)

   Exploratory Science

Seamounts are isolated submarine mountains and hills that rise to an elevation of 1000m or more above the ocean floor. They are distributed throughout the world's oceans. Although only about 1000 have been named, it is estimated there may be over 30,000 seamounts in the Pacific Ocean alone. The biology and ecology of seamounts has been discovered and studied only in recent years. Although relatively few seamounts have been sampled carefully, seamounts are of high interest for conservation because some support highly unique and endemic faunas.

Seamounts represent potentially large pools of undiscovered biodiversity in the oceans. Average levels of endemism (species on one seamount or seamount chain and nowhere else) in the oceans are probably at least 15% and have been documented as high as 30-50% in some regions. In addition, they may be sites of speciation, refuges for rare species, and stepping-stones for distribution. While these functions are not fully understood, they indicate that seamounts may have important roles in the speciation and distribution of species in the oceans.

Seamounts are increasingly under threat from deep-sea fishing activities. Many characteristic species on seamounts are very long-lived, and their biological communities can take hundreds and even thousands of years to develop. However, newly developed fisheries for deep-sea species of fish are now altering these habitats faster than they can be studied. It is likely that nearly all shallow seamounts have experienced some degree of fishing pressure already. Trawling on deep seamounts became possible with the constant development and progress of fishing gear technology. Large-scale commercial fishing began in the 1960s for orange roughy, pelagic armorhead, hoki, oreos and related species, leading to collapse of many of these populations by the 1990s. Current management efforts in Australia and New Zealand include closure of parts of the seamount fisheries, but developing fisheries in other parts of the world are relatively unregulated. Collateral damage from deep-sea trawling is a significant effect, destroying complex, long-lived and poorly known benthic communities in the process of catching fish. One study done on Tasmanian hills indicated that unfished hills had twice the biomass of fished ones, and only 10% bare rock compared to 95% bare rock on fished sites (Koslow et al 2001).

Only ~200 of the estimated 100,000+ seamounts have been sampled biologically, and this sampling is often very incomplete, documenting only a few species. While it is not feasible to sample all of the seamounts in the oceans, targeted sampling is required to fill in the current gaps and be able to predict from the known to the unknown. Existing gaps that should be addressed by future research includes:

1. Understudied regions. Areas such as the southern Pacific/Southern Ocean have high densities of seamounts and virtually no research. The Indonesian area is also little explored but likely to support highly endemic and diverse communities given that it is an area of speciation for many taxa and habitats. A comprehensive effort is needed to get representative sampling from a range of latitudes, ocean regions, and distance from land. In addition, certain geological or topographic types of seamounts, including very deep and soft-sediment seamounts are not well known.

2. Poorly known biology. Fishes have received by far the largest amount of sampling, yet seamounts support a diverse array of invertebrate species. "Top-to-bottom" sampling at several seamounts that study the entire community from bacteria/viruses through macro-fauna are needed. These studies should include distributional information, and population genetics research to determine the relative isolation and evolutionary history of seamount species.

3. Time-series monitoring to follow how seamount environments and communities change over time.

4. Fishing impact studies should include assessments of bycatch and overharvesting in seamount fisheries, as well as habitat damage and recovery times.

5. Technology development is needed to create new tools for exploring and sampling remote, deep, and difficult-to-access seamounts. Remote operated and autonomous vehicles that can do sonar and video mapping, and collect biological samples are promising approaches.

6. Information aggregation is needed to understand large-scale patterns on seamounts, which are currently difficult to assess because data is spread among many sources and hard to access. A comprehensive effort to analyze global data and create predictive models will help guide future research and conservation efforts on seamounts. The Web program SeamountsOnline has started an effort to integrate global data from seamounts for easier analysis and synthesis.

SeamountsOnline
Censeam