Many marine resource management tools, such as reserves or multiple-use zones, control user activities in order to benefit an area’s organisms. From a management point of view, this approach is relatively simple to apply and enforce, but its effectiveness in managing motile organisms such as reef fishes may depend on whether the organism can move from one zone to another. For example, kelp forests are spatially patchy and may have different levels of ‘connectedness’ for different fish species. Some fishes might not cross large sand patches to move from one rock to
another but might frequently move among rock pinnacles separ-ated by rocky habitat ‘corridors.’ If the boundary between an area that is closed to fishing and one that is open to fishing is highly connected (from a fish’s point of view), then the level of protection anticipated by the no-fishing zone may not be as high as assumed.
Over the past two years the Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO) has been conducting a study -- funded jointly by the National Undersea Research Program (NURP) and PISCO -- to examine how fishes move in kelp
forest landscapes. We are using the commercially available VEMCO Radio Acoustic Positioning system (VRAP) of acoustic tags and moored receivers to track movement patterns of blue
rockfish, kelp rockfish, and kelp greenlings on the Monterey Peninsula. Sonic tags have been surgically implanted in thirty
individuals each of the three species in kelp forests with different levels of patchiness and connectivity. The receivers triangulate the positions of each tag every three minutes and radio this information to a computer base station at the Monterey Bay Aquarium. Computer software then calculates the position of each individual and overlays it in real time over bathymetric maps.
|Figure 1. A week in the life of a blue rockfish. A plot of movement rates (the distance moved among triangulations as a function of time) reveals variability in activity. Each dot represents a position fix, and the shaded regions are night-time periods. This blue rockfish was more active during daytime, but the amount of activity varied day to day.
This study was initiated in the summer of 2003 and is now in its second year. Data analysis is in a preliminary stage, but some interesting patterns are beginning to emerge. Initial results suggest that kelp rockfish typically occupy a range approximately 20x20 meters in area, while kelp greenlings occupy a home range from 20x20 to 40x40 meters, depending on habitat quality. In contrast, blue rockfish move over larger areas (hundreds of meters), with occasional movements in excess of 400 meters. However, all species have been observed to make long forays away from their ‘typical’ home range. For example, one kelp rockfish crossed 150 meters of sand to move to an isolated rock patch, then ‘leap-frogged’ across a series of rock patches for a distance of 350 meters, and returned
by the same route four days later.
|Figure 2. After tagging a fish, divers return it to its capture location to reduce predation. photo Tara Anderson, USGS/NMFS
An unforeseen result from this project has been information on the animals’ daily activity patterns. Blue rockfish, for example, are typically motile during the day, with a lot of day-to-day variability in their movement rates. (See Figure 1) The final analysis of these data will enable information on movement rates and the position of fishes to be overlaid on habitat topography and connectedness as well as biological characteristics such as kelp density.
In addition to contributing to ecological understanding about
fish movements in kelp forest landscapes, this project has important societal implications. Marine protected areas (MPAs) have received increased attention as a tool to manage and conserve marine resources -- by protecting habitat and ecological function and
supplementing traditional fisheries management by protecting a subset of a fishery stock from exploitation. However, predicting how effective a reserve will be requires an understanding of the relationship among the size and shape of a reserve, fish home ranges, and habitat complexity. This study represents one of a handful of studies that can explicitly link habitat use and move-ment of individuals to remotely sensed habitat maps within and adjacent to existing marine reserves. The development of such
an approach and the information gleaned from this study are
fundamental to the sound development and evaluation of MPAs
for reef fish conservation throughout coastal, temperate oceans.
Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO)
and School of Marine Biology & Aquaculture, James Cook University
of North Queensland
Terrestrial landscapes have been well mapped and documented. Maps are available that provide a wealth of spatial information on landscape features (e.g., elevation, slope) and composition (e.g., rivers, mountains, farms, cities). We also have maps and information on the distribution of the flora and fauna that inhabit these different landscapes. Consequently, one might expect similar maps and information to be available for our marine environment. Alas, we know relatively little about the habitats and organisms that exist on our seafloors.
A key mission of the national marine sanctuaries
is to understand and manage the marine environment within sanctuary boundaries. This requires a sound knowledge of the composition and complexity of the marine environment, its habitats, and the organisms that occur there.
|Figure 1. Low-lying cobble habitats inhabited here, 110 meters off Point Pinos, by basket stars (Gorgonocephalus eucnemis), vermilion star (Mediaster aequalis), and half-banded rockfish (Sebastes
semicinctus). photo Rick Starr/Noaa
In April 2004 a team of scientists from the U.S. Geological Survey (USGS), the National Oceanic and Atmospheric Administration (NOAA) Sanctuaries,
and NOAA Fisheries collaborated on a twenty-day research cruise to map and describe the seafloor
across the continental shelf from the northern reaches of the Cordell Bank National Marine Sanctuary (CBNMS) to the southern reaches of Monterey Bay.
The survey’s goals were to map the geology, habitat, and
biodiversity within regions of the three adjacent national marine sanctuaries: Monterey Bay (MBNMS), Gulf of the Farallones (GFNMS), and Cordell Bank. This project aimed to build on
existing data but in many places provided our very first glimpses
of the seafloor.
Research surveys were conducted from April 1 to April 21 aboard the 225-foot NOAA ship McArthur II. Our research team, including Roberto Anima, John Chin, and Fred Payne (USGS); Dale Roberts and Dan Howard (CBNMS); and Jean de Marignac and Erica Burton (MBNMS), worked day and night to collect information on the seafloor in the three sanctuaries. During the day, side scan sonar was used to map seafloor geology over large areas. At night, a towed camera-sled was used to film these habitats and document the organisms living there. USGS scientists used a Klein 3000 side scan sonar system to acoustically image several previously unmapped sections of the seafloor within each sanctuary (e.g., Pescadero Reef in the MBNMS) and to extend coverage from earlier missions (e.g., Fanny Shoals in the GFNMS). Hundreds of hours of video footage were then collected from multiple transects with the towed camera, providing a wealth of information about
the types of habitat and life found on the seafloor and about the distributions of geological features, habitats, and organisms across and along the shelf.
A variety of seafloor habitats and marine creatures were identified within the sanctuaries. For example, sand-wave habitats were verified in areas around Point Pinos and were occupied by sand dabs and schools of juvenile rockfish. Sediment-ripple habitats were common across regions of the shelf and were often densely populated with white brittle stars with their bodies buried in sediment. Low-lying cobble habitats were verified along the mid-shelf region south of Monterey Canyon and were occupied by encrusting organisms such as basket stars, sponges, and gorgonian corals and by fishes such as the half-banded rockfish, Sebastes semicinctus. (See Figure 1.) High-relief bedrock habitats, although less common on the mid- to outer shelf, were also surveyed and characterized. These habitats were occupied by encrusting invertebrates, vase sponges, large anemones, gorgonians, and many rockfish species.
An integral aspect of this project involved the development of
a rapid-data-entry protocol whereby seafloor categorizations and descriptions were recorded in real time. Although requiring effort, the protocol enables seafloor data to be processed while at sea, including the production of maps within hours of data collection. This, in turn, dramatically reduces the time before seafloor information can be made available to managers, stakeholders, and the public. Importantly, this approach also enables web users to view actual footage from locations of interest within weeks of survey completion (see www.mbnms-simon.org/other/moreLinks/ whats_new_mac.php).
The ability to map seafloor habitats within our sanctuaries and the creatures that inhabit them will help managers better protect these habitats, plants, and animals. Further, the knowledge of what is present today will provide the foundation to monitor future changes in these important resources.
U.S. Geological Survey (USGS-CMG) and NOAA Fisheries
(NMFS, SWFSC), Santa Cruz Laboratory