Abstract

In October 1975, the Smithsonian put into operation its Scientific Event Alert Network (SEAN), which largely took over and expanded the system of collecting stranding data which we had started in 1972. 1976 was the first full year of operation of the new system, which managed to compile information on several hundred strandings on a more or less nationwide basis.  Although primarily effective on the Atlantic coast, foreign and domestic coverage has been expanding.  The network has proved to be an effective system for timely dispersal of information on strandings, and the data gained have provided a number of new insights into the biology of some of the species regularly occurring along our coasts. Of particular interest have been mass strandings, seven of which have been investigated in the last twelve months.  Pathological findings have been variable, dependent in large part on the condition of the specimens upon recovery, but a number of pathological conditions are beginning to appear as common elements in stranded individuals of some species.

Notes

Phocoena - These animals die off-shore, drift along the bottom and are somewhat decomposed by the time they reach the beach.

Tursiops - Beached calves appeared to be stillbirths, but it was difficult to tell if the lungs had been inflated due to decomposition.  The ductus arteriosus closes quite late in Tursiops so this is not a good indicator of birth. The muscle of the fetus is very pale but decomposition of the fetus usually prevents determination of this. The position of the dorsal fin can indicate whether or not the animal is a fetus.  At birth, the dorsal fin is folded over. Later it becomes firmer and stands up.  If one can fold the fin over and it stays, it is likely a fetus.

Estimating the population size of Tursiops is very difficult since groups of animals are sex and age segregated.

Weaning usually occurs at approximately 150 cm of length.  This was estimated by the presence of fish in the stomach or parasites derived from a fish diet in the gastrointestinal tract.

Pathology

1. Chronic pancreatitis was the most common finding.  Often half of the pancreatic tissue was fibrosed. This was likely associated with trematodes in the hepatopancreatic duct since pancreatitis was found mainly in young animals, less than 2 meters in length.  Animals which have lived to maturity likely have overcome the trematodes and become resistant.  Young animals likely either die or eliminate the parasites and go on to become adults.
2. Liver abscess
3. Metritis (maybe)
4. Trematodes in pterygoid air sinuses (Nasotrema); large numbers of these parasites cause inflammation.