James Lindholm

Site utilization by Atlantic Cod (Gadus morhua) in off-shore gravel habitat as determined by acoustic telemetry: Implications for the design of marine protected areas

We quantified the site utilization of offshore gravel habitat by Atlantic cod (Gadus morhua) using acoustic telemetry. An omni-directional receiver was deployed inside Stellwagen Bank National Marine Sanctuary during Summer 2001 in an area that excluded commercial fishing for demersal fishes. Fish were collected using hook and line, tagged externally with coded acoustic pingers, and released on the seafloor using an elevator within the range of the receiver. Observations were made over 120 days. The total number of days that individual fish were recorded was up to 120 days and a total of 37% of all tagged fish showed high site fidelity to the study area.

In Situ Tagging and Tracking of Coral Reef Fishes from the Aquarius Undersea Laboratory

T I N T R O D U C T I O N he use of acoustic telemetry to track the movements of marine fishes is now a commonly employed method (see other papers this issue), producing data on fish home ranges (Zeller, 1997; Bolden, 2001; Simpfendorfer et al., 2002), habitat-specific movement (Lindholm and Auster, 2003; Lowe et al., 2003; Cote et al., 2004), and movement relative to the boundaries of marine protected areas, or MPAs (Zeller and Russ, 1998; Meyer et al., 2000; O’Dor et al., 2001; Starr et al., 2001; Lowe et al., 2003). While the specific approaches to the use of acoustic telemetry vary widely depending on the species targeted for study and the habitat in which the targeted species occurs, all projects share four common elements: 1) the collection of fishes, 2) the tagging of fishes, 3) the release of tagged fishes, and 4) the tracking of tagged fishes. Also common to most studies is the conduct of each of these elements from the surface, where the extraction of fishes from their natural environment can create difficulties. Fishes are often collected from the surface via baited traps, long-lines, trolling and traditional angling. Fish brought to the surface for tagging can experience barotrauma, or pressure-related stress. This is particularly true with deepwater fishes that have air bladders (Starr et al., 2000). Thermal shock can also result from bringing a fish to the surface and then aboard a surface vessel (Kelsch and Shields, 1996). Each of these stressors can kill a fish outright or have sub-lethal effects that increase the fishes’ vulnerability to other stressors and may preclude a fish from being tagged. Telemetry projects on fishes typically involve either the attachment of an acoustic transmitter externally (e.g., Bradbury et al., 1995; Lindholm and Auster, 2003; Cartamil and Lowe, 2004), intragastric insertion of the transmitter down the pharynx into the stomach (Bridger and Booth, 2003), or surgical implantation of the transmitter inside the peritoneal cavity of a fish (e.g., Zeller, 1997; Starr et al., 2000; Bolden, 2001; papers in this volume). Where surgical implantation is used, incisions can be closed with sutures (e.g., Thoreau and Baras, 1997), surgical staples (e.g., Mortensen, 1990) or an adhesive (e.g., Nemetz and MacMillan, 1988). Implantation is normally conducted on a padded, v-shaped surgical board (Winter, 1996) and may involve fresh flowing seawater over a fish’s gills, or covering the fish with a damp towel. Each approach involves a series of trade-offs that will vary depending on the species selected for tagging, though most approaches involve exposure of the fish to air and sunlight for some period of time during surgery. Following some period of observation in a live-well on board a research vessel, tagged fishes are either released directly over the side of the boat or are lowered to the seafloor in some form of a release device (e.g., Starr et al., 2000; Lindholm and Auster, 2003). Though the use of a release device can increase researcher confidence that the fish has indeed returned to the seafloor or at the depth from which it was collected initially, both forms of release involve a high measure of uncertainty. The fate of these fish post-release is difficult to determine, i.e., did the transmitter malfunction, was the tagged fish consumed by a predator, is the fish dead and lying on the seafloor? This problem is lessened when data are collected indicating the tagged fish is moving. However, where the post-release data are limited or non-existent, it is often impossible to know the fate of the fish without in situ observation.

Dynamic modeling for marine conservation

Part I: Concepts and Techniques.- Introduction.- Modeling in STELLA.- Predator-Prey Dynamics.- Epidemic in the Marine System.- Impacts of Fishing Pressure on Mean Length of Fish.- Spatial Fisheries Model Part II: Applications.- Modeling Atmosphere-Ocean Interactions and Primary Productivity.- Impact of Dynamic Light and Nutrient Environments on Phytoplankton Communities in the Coastal Ocean.- Eelgrass Dynamics.- Life-stage Based Recovery Dynamics of Marine Invertebrates in Soft-sediment Habitats.- Horseshoe Crabs and Shorebirds.- Kelp, Urchins and Otters in the California Region.- Nile Perch Population Dynamics in Lake Victoria: Implications for Management and Conservation.- Dynamics of Multiple Fish Species under Variable Levels of Exploitation.- Fish Population Responses to Seafloor Habitat Alteration: Implications for the Design of Marine Protected Areas.- Management of the Commons: Social Behavior and Resource Extraction.- Cod Aquaculture.- The Global Shrimp Market.

Patterns in the Local Distribution of the Sea Whip, Halipteris willemoesi , in an Area Impacted by Mobile Fishing Gear

The sea whip, Halipteris willemoesi (Octocorallia: Pennatulacea) is a sessile macro-invertebrate common on the continental shelf and slope of western North America. It is an erect, colonial organism that is anchored to the seafloor by a burrowing peduncle (Wilson et al., 2002). Members of the family have been reported at water depths ranging from 50 to 6200 m (Williams, 1999; Stone, 2003). Along the central coast of California (USA) sea whips are frequently observed along the outer continental shelf in low densities (< 1 m ) and are periodically found in dense patches (>2 m ). The factors contributing to observed sea whip densities have not yet been explained. A variety of organisms, including rockfish (Kreiger, 1993; Brodeur, 2001), sea horses (Choo and Liew, 2003), weathervane scallops (Masuda and Stone, 2003) and basket stars (de Marignac et al., in review) have been observed to associate with H. willemoesi or other pennatulid species. As attributes of animal habitat, sea whips may provide cover from predation and facilitate animal feeding higher in the water column. The vulnerability of the H. willemosi to impacts from trawling activity remains unclear. Studies of age and growth indicate that sea whip life spans may exceed 50 yrs (Wilson et al., 2002), indicating that any impacts from trawling could persist for decades. Troffe et al. (2005) found differential impacts to H. willemosi from beam trawls and prawn traps. They theorized that sea whips may be able to withstand impacts from mobile fishing gear by bending and/or re-attaching to the sediment following disruption. Both bending and reattachment have been observed in other pennatulid species in the presence of fishing activity (Eno et al., 2001). However, in the Gulf of Alaska, 55% of individual sea whips (Stylea spp.) were either broken or had been extracted from the sediment following a single pass of a trawl (Freese et al., 1999). ImR E S E A R C H N O T E Current Address: Institute for Applied Marine Ecology, California State University Monterey Bay

Predator-Prey Dynamics

Historically, many of the models of the natural world, both marine and terrestrial, have involved only a single species, conceptually separating the species of interest from its environment. In fact, species are in continuous contact with other organisms and their physical environment. The models we address in this book all involve relationships between marine organisms and between organisms and their surrounding physical environment. Several of the relationships will reflect some form of predator-prey interaction—sea birds preying upon horseshoe crabs, sea otters on sea urchins, fish on fish, and ultimately, humans on fish.

Modeling in STELLA

To begin our exploration of modeling with STELLA we first develop a basic model of the dynamics of a population—let’s say of humpback whales (Megaptera novaeangliae). In building the model, we will utilize all four of the graphical tools for programming in STELLA. The CD has a demo of the software. The appendix also describes how to install the STELLA software and models of the book. Follow these instructions before you proceed. After installation, open the STELLA software. On the screen appears a window within which you can develop your model. If you instead wish to open an already existing model, you need to close the new model that you have created upon opening STELLA. Go to the “File” pull-down menu, select “Close Model,” then select “Open Model” and navigate to the model of your choice.

Reflections on the Parts and the Whole

The marine environment is in peril, largely as a consequence of human action—and inaction. Over-fishing, habitat alteration, pollution, and global climate change lead the long list of human-induced impacts to delicate marine ecosystems worldwide, many of which we have discussed here. The implications of these impacts, for the global ecosystem and therefore for humanity as well, are considerable. They include the loss of biological diversity, increased susceptibility to further disruptions, and ultimately a decline in species directly exploited for human uses. This book has been about modeling and marine conservation. We could have easily called it Dynamic Modeling for Marine Preservation, for preservation of the natural world has its obvious merits and is deserving of a book all its own.

Dynamics of Multiple Fish Species Under Variable Levels of Exploitation

Marine fish populations are among the most heavily exploited populations on Earth. Fish populations are subject to the fluctuations of numerous environmental factors and to economic changes within the fishing industry that are all but steady over time. The cumulative effect of these influences upon fish populations has left commercial fisheries around the globe struggling to adjust to precipitously declining fish populations, while simultaneously striving to maintain economic viability and cultural identity in the fishing communities involved (World Resources Institute 1994).

Fish Population Responses to Sea Floor Habitat Alteration

Attention to the role of sea floor habitat in the dynamics of fish populations has increased recently in both the management and scientific communities around the globe. For example, the U.S. Sustainable Fisheries Act of 1996 (the reauthorized Magnuson Fishery Conservation and Management Act) requires that the federal Fishery Management Councils identify essential fish habitat (EFH) for all the fish and shellfish species for which fishery management plans are enacted (50 CFR 600 et seq.). The effective designation and ultimate conservation and protection EFH requires data on fish population dynamics and the ecological influences of habitat on those dynamics for each life-history stage.