The Lakewood View

Monday, October 8, 2007

Whales A difficult Existance!

Life is not Easy!

Life for the Creatures of the Sea is difficult as well. We should not forget that humans have no natural predators. What follows is a brief excerpt from a bilogical paper on a particular species of Whales which fall into the Toothed Whale category.
AhMbdvd 10/9/07

The rate of predation on narwhals by killer whales and polar bears is unknown but may be significant. When killer whales are present narwhals hide in broken pack ice or shallow nearshore waters (Freuchen and Salomonsen 1958; Steltner et al. 1984; Campbell et al. 1988; Reeves and Mitchell 1988; Gonzalez 2001). They breathe quietly to avoid detection and stop vocalizing instantly when killer whales approach (Ford 1987). Their fear is such that they will ignore humans.

Killer whales appear to prefer non-tusked narwhals (Gonzalez 2001). Hunters in the Repulse Bay area see killer whales more frequently now than in the past and have expressed concern about killer whale predation on narwhals (Gonzalez 2001). The frequency of seasonal visits by killer whales to Hudson Bay, and their effect on the narwhals is unknown (Reeves and Mitchell 1988; DFO 1998a; Stewart et al. 1991). Killer whales may have driven narwhals close to Cape Dorset in the 1960s (Higgins 1968), south to Arviat in 1988 (W. Angalik, pers. comm. in Stewart et al. 1991), and into shallow water in the Repulse Bay area in 1999 (Gonzalez 2001). The latter resulted in an unusually large harvest of narwhals by Repulse Bay ...

The narwhal’s ability to dive deeply and hold their breaths for long periods enables them to move long distances under water to avoid hunters and to locate areas where they can surface to breathe. In the deep waters of Baffin Bay, narwhals dive to at least 1500 m and daily make dives to depths of over 500 m (Heide-Jørgensen and Dietz 1995; Heide-Jørgensen et al. 2002). They can remain under water for at least 26.2 minutes when foraging (Laidre et al. 2002) and up to 30 minutes when pursued by Inuit (Gonzalez 2001). Their diving ability makes it difficult to obtain accurate population estimates. Variations in narwhal diving behaviour related to season, location, and sex of the animal complicate the correction of population survey data for animals that were submerged deeply enough to be invisible to the survey...

residents of 13 communities hunt animals from the Baffin Bay population, while the Hudson Bay narwhals are hunted mainly by residents of Repulse Bay and sometimes by residents of 6 other communities (Table 1). Narwhal are also hunted by the Kugaaruk community following the community-based management system, while Taloyoak and Gjoa Haven have a yearly limit of 10 narwhals each. Most narwhals are harvested in July and August (Donaldson 1988; Gamble 1988; Guin and Stewart 1988; J. Pattimore, pers. comm. 1986). The hunts begin earlier in the year in Pangnirtung (April), Pond Inlet and Arctic Bay (May) and end later in the year in Clyde River and Qikiqtardjuak (October).

The actual number of narwhals killed during these hunts is higher than the number landed, but unknown because few data were collected on the number of animals that were killed and lost. These losses vary depending upon the location, weather, hunter experience, and type of hunt (e.g. floe edge, ice crack, open water). They also vary from year to year. Thus loss rates cannot be extrapolated from one season to another or from one community to another (Weaver and Walker 1988; Roberge and Dunn 1990). Loss rates are typically highest at the floe edge and lowest during the open water hunt (Roberge and Dunn 1990).

Comparison of these rates between studies is confounded by the fact that some studies considered only whales killed and lost, while others also considered whales that were wounded and escaped. The former method tends to underestimate the total kill, and the latter to overestimate it. These two extremes provide a range within which the actual loss rates should lie. Loss estimates from the community-based management hunts in 2001 suggest that on average at least 19 (SD 11; killed and lost only) and perhaps as many as 46 (SD 5; killed and lost plus struck and escaped) animals are lost for every 100 landed (Table 2).

These crude annual loss rate estimates are comparable to those from earlier studies, most of which were for portions of the annual hunt (e.g. Hay and Sergeant 1976; Finley et al. 1980; Kemper 1980; Finley and Miller 1982; Weaver and Walker 1988; Roberge and Dunn 1990). The collection of struck and lost data is a key contribution of the community-based management program to improving estimates of hunting mortality. Losses result in part from the fact that narwhals are often shot before they are harpooned (Bruemmer 1971; Stewart et al. 1995). Loss rates are greater among animals that are not harpooned (Gonzalez 2001). In 1979, Pond Inlet hunters tried using harpoon guns to reduce loss rates.

This technology proved to be much less practical than .303 calibre rifles and hand-thrown harpoons for killing and securing narwhals (Finley and Miller 1982). In the Pond Inlet area, a high proportion of harvested animals have old bullet wounds
(42% Finley et al. 1980; 23% Finley and Miller 1982). Many of the communities participating in community-based management require hunters to use harpoons as a means of reducing the number of whales that are struck and lost

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