Oiled Sea Otter Capture Course

Capture and Restraint

Methods for capturing pinnipeds have been described in the literature (Geraci and Lounsbury, 1993). These techniques are generally restricted to the smaller otariids and phocids. Most methods rely on the use of nets to capture individual animals. Alternatively, mass capture of several animals is possible and has been described for fur seals. Chemical capture and restraint has been extensively reported and recently reviewed for marine mammals (T. D. Williams et al., 1990). Telazol(R) (8-9 mg/kg) has proven to be reliable and safe for immobilizing polar bears under a variety of field conditions (Stirling et al., 1989).

The potential for physically or chemically capturing marine mammals will depend on the number of target animals, the number of nontarget animals, and the terrain. Capture is usually limited to the land or ice as capture techniques at sea are generally considered hazardous. Because of the difficulties, it is important to be realistic when selecting target animals. Adult seals and bears that are fouled with oil and capable of avoiding capture by rapidly entering the sea should probably not be captured. Their condition can be monitored visually, especially if they are marked with projectile paint pellets or another identifiable tag.

We recommend capturing unoiled animals for use as a control group. These animals are especially useful for establishing normal values for body mass, clinical state, and hematological and biochemical constituents. Such controls also enable the researcher or veterinarian to differentiate between anomalies caused by the oiling and those associated with disturbance by the cleaning method. Control animals should be marked for the duration of the study.

Many chemical compounds used for capture or immobilization interfere with thermoregulation, compounding the problems already faced by an oiled fur seal or polar bear. The greatest concern is for animals in polar and subpolar environments. Any type of capture or restraint will impose some form of stress, which must also be considered when handling these animals. Fortunately, pinnipeds and polar bears generally tolerate capture and transportation better than sea otters; they do not appear as susceptible to the capture myopathy or “capture stress syndrome” described for sea otters (Williams and VanBlaricom, 1989).

Once an animal has been captured, it may be necessary to retain it for detailed clinical evaluation, intensive treatment, or simply to await the removal of oil from its environment. In the latter instance, it is preferable to assemble holding pens on location for pinnipeds. Such pens must: 1) be designed for quick and easy construction, 2) have the intrinsic strength to contain the animals, and 3) adequately meet the behavioral and physiological needs of the species and age class to be held. Following the sinking of the Sanko Harvest, more than 200 New Zealand fur seal pups were held in five temporary pens constructed on two separate islands. The pens were made from chicken wire and averaged 5 m by 3 m in size, with a fence height of 1.2 m. Shade was provided by tarpaulins. These structures held the animals for up to two and a half days until the oil had been cleaned from the surrounding areas. Overcrowding in one pen led to the death of six pups, but otherwise the pens were adequate (Gales, 1991).

When permanent holding facilities are required (as with polar bears), it may be necessary to transport the animals from the capture site. Such undertakings are logistically challenging, but allow intensive study of the affected animals. A major problem associated with longterm holding of oil-fouled pinnipeds and polar bears is the stress associated with removing an animal from the wild. Even healthy individuals taken into captivity may experience difficulties during acclimation, particularly in learning to accept food. The problems are intensified if the animal is clinically compromised. Furthermore, some species and age groups are more adaptable than others. (See Chapter 1.)