scholarly journals Effects of fine-scale oceanographic features on the distribution and movements of harbour porpoises Phocoena phocoena in the Bay of Fundy

2005 ◽  
Vol 295 ◽  
pp. 279-293 ◽  
Author(s):  
DW Johnston ◽  
AJ Westgate ◽  
AJ Read
Keyword(s):  
Bay Of Fundy ◽  
Fine Scale ◽  
Phocoena Phocoena

Changes in Growth and Reproduction of Harbour Porpoises, Phocoena phocoena, from the Bay of Fundy

1990 ◽  
Vol 47 (11) ◽  
pp. 2158-2163 ◽  
Author(s):  
Andrew j. Read ◽  
David E. Gaskin
Keyword(s):  
Sexual Maturity ◽  
Prey Availability ◽  
Simultaneous Increase ◽  
Bay Of Fundy ◽  
Commercial Fisheries ◽  
Phocoena Phocoena ◽  
Pronounced Change ◽  
Younger Age ◽  
Incidental Mortality ◽  
Growth And Reproduction

Changes in the growth and reproduction of harbour porpoises from the Bay of Fundy are described by comparing samples collected in 1969–73 and 1985–88. The most pronounced change was an increase in the length of calves, from 92.1 cm (SE 1.6) in 1969–73 to 108 cm (SE 1.3) in 1985–88. Females in 1985–88 attained sexual maturity at a significantly younger age (3.44 yr) and shorter length (143 cm) than females from the older sample (3.97 yr and 147 cm). These changes may be attributable to an increase in prey availability to individual porpoises. This presumed increase in prey availability may have resulted from a decrease in porpoise density caused by incidental mortality in commercial fisheries, a simultaneous increase in prey abundance, or a combination of these factors.

Mitigation of harbour porpoise (Phocoena phocoena) by-catch in the gillnet fishery in the lower Bay of Fundy

1999 ◽  
Vol 56 (1) ◽  
pp. 113-123 ◽  
Author(s):  
Edward A Trippel ◽  
Michael B Strong ◽  
John M Terhune ◽  
Jeremy D Conway
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Field Testing ◽  
Harbour Porpoise ◽  
Clupea Harengus ◽  
Bay Of Fundy ◽  
Phocoena Phocoena ◽  
By Catch ◽  
Catch Rates ◽  
Wind Sea

Demersal gill nets equipped with acoustic alarms reduced harbour porpoise (Phocoena phocoena) by-catch rates by 77% over those without alarms in the Swallowtail area of the lower Bay of Fundy during field testing in August 1996 (68% reduction) and 1997 (85% reduction) (both years combined, three harbour porpoises in 249 alarmed nets versus 14 harbour porpoises in 267 nonalarmed nets). The alarms spaced 100 m apart along the net floatline produced a 0.3-s pulse at 10-12 kHz every 4 s at a level of 133-145 dB re 1 µPa at 1 m. In conditions of no rain and low wind (Sea State 0-2) the alarms were presumed to be clearly audible to harbour porpoises at ranges of 0.1-0.6 km. Catch rates of Atlantic herring (Clupea harengus), Atlantic cod (Gadus morhua), and pollock (Pollachius virens) were not significantly different in alarmed and nonalarmed nets (except in one season when pollock were caught in lower numbers in alarmed nets). Harbour porpoise by-catch and herring movements may be linked. During years of low herring abundance, we also observed low harbour porpoise entanglement rates.

Diving behaviour of harbour porpoises, Phocoena phocoena

1995 ◽  
Vol 52 (5) ◽  
pp. 1064-1073 ◽  
Author(s):  
Andrew J. Westgate ◽  
Andrew J. Head ◽  
Per Berggren ◽  
Heather N. Koopman ◽  
David E. Gaskin
Keyword(s):  
Data Collection ◽  
Dive Depth ◽  
Maximum Depth ◽  
Diving Behaviour ◽  
Bay Of Fundy ◽  
Phocoena Phocoena ◽  
Diel Pattern ◽  
Maximum Capacity ◽  
Gill Nets ◽  
Free Ranging

The diving behaviour of seven free-ranging harbour porpoises (Phocoena phocoena) was examined using time–depth recorders. In total, 8167 individual dives were recorded over 254 h. The longest period of data collection from an individual was 106.1 h. Mean dive depths and durations ranged from 14 ± 16 to 41 ± 32 m, and from 44 ± 37 to 103 ± 67 s, respectively. The maximum recorded dive depth and duration was 226 m and 321 s. This performance may not represent the maximum capacity of harbour porpoises but rather the maximum depth of the study area. Individual dives had similar rates of descent and ascent, which ranged from 1.1 ± 0.6 to 2.3 ± 1.4 m/s, and from 0.9 ± 0.6 to 2.1 ± 1.4 m/s, respectively. Two porpoises with monitoring periods >2 days demonstrated a diel pattern in their diving, making fewer, but deeper dives at night. Comparison of the diving behaviour of harbour porpoises with data on the depth of 140 porpoises entanglements in groundfish gill nets in the Bay of Fundy showed these seven porpoises made between 22 and 70% of dives to depths (range 20–130 m) where the majority of entanglements were reported.

Individual and geographical variation in pigmentation patterns of the harbour porpoise, Phocoena phocoena (L.)

1994 ◽  
Vol 72 (1) ◽  
pp. 135-143 ◽  
Author(s):  
H. N. Koopman ◽  
D. E. Gaskin
Keyword(s):  
British Columbia ◽  
New Record ◽  
Geographical Variation ◽  
Individual Recognition ◽  
Harbour Porpoise ◽  
Bay Of Fundy ◽  
Phocoena Phocoena ◽  
Geographically Isolated

Photographs of 393 harbour porpoises (Phocoena phocoena (L.)) from the waters of Denmark (n = 224), Japan (n = 19), and Canada (Bay of Fundy (n = 95), Gulf of St. Lawrence (n = 40), and coast of British Columbia (n = 15)) were analyzed for variation in pigmentation patterns. Animals were classified according to morphs of each of 12 pigmentation characters. Patterns were not unique to particular areas and cannot be used as a tool for absolute discrimination among geographically isolated groups of porpoises. However, statistical frequencies of certain morphs of seven characters varied significantly among the five geographical groups, matching some of the subpopulations proposed by Gaskin in 1984. Pigmentation patterns of harbour porpoises were unique to each animal and were not gender dependent. Variation in pigmentation patterns may have implications for intra-individual recognition. All porpoises showed bilaterally asymmetrical pigmentation, providing a new record of consistent asymmetry in an odontocete species.

Incidental mortality of harbour porpoise (Phocoena phocoena) by the gill-net fishery in the lower Bay of Fundy

1996 ◽  
Vol 53 (6) ◽  
pp. 1294-1300 ◽  
Author(s):  
E A Trippel ◽  
J Y Wang ◽  
M B Strong ◽  
L S Carter ◽  
J D Conway
Keyword(s):  
Harbour Porpoise ◽  
Bay Of Fundy ◽  
Phocoena Phocoena ◽  
Gill Net ◽  
Incidental Mortality

Postnatal growth and allometry of harbour porpoises from the Bay of Fundy

1997 ◽  
Vol 75 (1) ◽  
pp. 122-130 ◽  
Author(s):  
Andrew J. Read ◽  
Krystal A. Tolley
Keyword(s):  
Growth Rates ◽  
Growth Curves ◽  
Postnatal Growth ◽  
The Body ◽  
Harbour Porpoise ◽  
Body Region ◽  
Bay Of Fundy ◽  
Commercial Fisheries ◽  
Phocoena Phocoena ◽  
Thoracic Region

We described patterns of growth and allometry from observations of 203 female and 198 male harbour porpoises, Phocoena phocoena, killed in commercial fisheries in the Bay of Fundy between 1985 and 1993. Gompertz growth curves were used to predict length, mass, and girth at physical maturity. Asymptotic sizes and growth rates were greater in females for all three characters. The pattern of allometry was consistent between sexes, but varied according to body region. The characters in the head and thoracic regions exhibited negative allometry, but those in the posterior of the body were isometric. Most characters showed the same growth rates for the two sexes, except those in the thoracic region, for which females exhibited faster growth than males. These results are consistent with those of several other studies of the harbour porpoise in which faster growth and larger sizes are attained by females.

Consumption of euphausiids by harbour porpoise (Phocoena phocoena) calves in the Bay of Fundy

1992 ◽  
Vol 70 (8) ◽  
pp. 1629-1632 ◽  
Author(s):  
Richard J. Smith ◽  
Andrew J. Read
Keyword(s):  
Fish Species ◽  
Prey Item ◽  
Stomach Contents ◽  
Harbour Porpoise ◽  
Bay Of Fundy ◽  
Phocoena Phocoena ◽  
Gill Nets ◽  
Meganyctiphanes Norvegica

We compared the contents of 31 stomachs of harbour porpoise calves killed in commercial gill nets in the Bay of Fundy between July and September, 1985–1991, with the stomach contents from 149 adult animals obtained from the same source between July and September, 1988–1991. The calves' most common prey item was the euphausiid Meganyctiphanes norvegica, found in 15 stomachs, whereas the adults fed primarily on clupeid and gadid fishes. Euphausiids were also found in the stomachs of several of these fish species, and we suggest that porpoise calves take euphausiids while their mothers are feeding on other euphausiid predators.

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