Characteristics of right whale (Eubalaena glacialis) and fin whale (Balaenoptera physalus) habitat in the lower Bay of Fundy were identified by quantifying physical and biological habitat variables and comparing them to the distribution of whales during the summer and autumn of 1989. Right whales were generally distributed over the Grand Manan Basin, where the bottom topography is relatively flat and the water column was stratified. Calanus finmarchicus, the principal prey species of right whales, was the predominant copepod taken in Zooplankton hauls, and the depth-averaged density (mean 1139/m3) was significantly greater where right whales were present. Fin whales were distributed mainly in shallower areas with high topographic variation that were likely well mixed or contained frontal interfaces between mixed and stratified waters. Herring (Clupea harengus) and euphausiids, both known prey of fin whales, were relatively abundant on echosounder traces in areas where fin whales were present. The habitats of both whale species were primarily characterized by high densities of principal prey species and the physical conditions that facilitate the accumulation of these prey.

1991 . Potential rates ot increase of a harbour porpoise (Phocoena phocoena) population subjected to incidental mortality in commercial fisheries. Can. J. Fish. Aquat. Sci. 48: 2429-2435.We estimated the potential intrinsic rate of increase (r) of the harbour porpoise (Phoesena phscoena) population in the Bay of Fundy and Gulf of Maine using empirical data on reproductive rates (rn,) and several hypothetical survival (I,) schedules. Schedules of I,, to maximum ages of 12 and 1 5 yr, were calculated from two potential natural mortality (n,) schedules combined with several schedules of incidental mortality (h,) estimates. The most realistic results were obtained when n, of won-calves were calculated from Caugley's (1 966. Ecology 47: 906-91 8) smoothed age-frequency equation for Himalayan thar (Hernitragus g'emlahicus) and applied in conjunction with a range of calf natural mortality estimates. This model indicates that harbour porpoises have a limited capacity for population increase, and populations are unlikely to sustain even moderate levels of incidental mortality (4% of the population per year). Extending the maximum age used in the models from 12 to 15 yr does little to increase estimates of r for the harbour porpoise population, and hence their susceptibility to incidental mortality.Nous avons estime le taux intrinsPqus potentiel d'augrnentation (r) de la population de marsouin cornn-tun (Phoccsena phocoena) dans la baie de Fundy et le golfe du Maine i I'aide de donnees ernpiriques sur les taux de reproduction (m,) et de plusieurs tableaux de survie (I,). bes tableaux de survie jusqu'j. des %ges de 12 et 15 ans ont etk calcules a partir de deux tableaux de mortalit6 naturelle possible (n,) combines 2I plusieurs tableaux d'estimations de mortalit6 accidentetle (h,). bes resultats les plus realistes ont 4te obtenus iorsque n, non-petits ont ete calcules a partir de I'equation de Caugley (1 966. Ecology 47: 906-94 8) pour la frequence lissee des ages de Hemitragus jemlahicus et appliques de concert avec une gamme d'estimations de la mortalite naturelle des petits. Ce rnodele indique que le marsouin commun a une capacite limitke de se multiplier et qu'il @st peke probable que les populations n-saintiennent des niveaarx meme rnoderks de rnortalite accidentelle (4 % de la population par at]). Porter la lirnite d'dge des modPles de 12 2 15 ans fait peu akegmenter les estimations du taux r de la population de marsouin cornmur], et donc leur susceptibilite 2I une mortalite accidentelle.

Polychlorinated biphenyls (PCBs), total DDT (DDT + DDE + DDD), dieldrin, heptachlor epoxide, chlordanes, and hexachlorobenzene (HCB) were found in blubber biopsies from endangered North Atlantic right whales (Eubalaena glacialis) in the Bay of Fundy and on Browns-Baccaro Banks. Analyses included four sex and age class composite samples from 1988, and 21 individual samples from 1989. Generally, PCBs demonstrated the highest wet weight residue levels (up to 1.9 micrograms/g), followed by total DDT (DDT + DDE + DDD) (trace to 0.47 micrograms/g). Relatively low residue levels in adult females suggest that transmammary organochlorine (OC) residue transfer occurs during lactation. The actual blubber residue loads may have been underestimated, because the samples were taken when the whales were depositing fat reserves and the samples may not have been representative of the remainder of the blubber.

1.Annual rate of increase ( r ) was estimated for the Hooker's sea lion (Phocarctos hookeri) using demographic models that incorporated age-specific estimates of reproductive rate (m,) and survival 2.In the absence of empirical estimates of natural mortality (n,), survival schedules were derived by combining a range of incidental mortality rates (h,) in commercial fisheries with estimates of n , for two species that exhibit similar life histories to Hooker's sea lions: northern fur seals (Callorhinus ursinus), model A, and Himalayan thar (Hemitragus jemlahicus), model B. Model A represented a population that would have a limited capacity for population increase; incidental mortality rates of mature females above about 1% would result in a population decline. Model B represented a population that, even in the absence of incidental mortalities, would just remain stable.3. If either of these models accurately represents the population demography of Hooker's sea lions, then these animals have limited capacity for population increase. They are constrained by relatively delayed maturity, moderate reproductive rates and short life spans.4. While absolute estimates of r from our models must be interpreted with caution, it is the responses of r to incidental mortalities and to increased natural mortality of pups that are most informative. Both models show r decreasing by 0.007-0.008 with a 0.01 increase in incidental mortalities of mature females. Both models also indicate that an increase in the natural mortality of pups by 0.027 will reduce r by 0.0055 or more.5 . Given the paucity of available empirical data, our results suggest that incidental mortalities of Hooker's sea lions in the trawl fishery for arrow squid (Nototodarus sloanii) should be minimized if a population decline is to be avoided.