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Minke Whales (minke + whale)

Distribution by Scientific Domains

Life Sciences	85%

Selected Abstracts

KILLER WHALE ATTACKS ON MINKE WHALES: PREY CAPTURE AND ANTIPREDATOR TACTICS

MARINE MAMMAL SCIENCE, Issue 4 2005
John K. B. Ford
Abstract We describe nine incidents of predation or attempted predation of minke whales (Balaenoptera acutorostrata) by mammal-hunting "transient" killer whales (Orcinus orca) in coastal waters of British Columbia, Washington, and southeastern Alaska. Pursuits of minke whales were characterized by prolonged chases on a straight heading at velocities of 15,30 km/h. In four of the nine cases the adultsized minke whale gradually outdistanced the killer whales, which abandoned the high-speed pursuit after 0.5,1 h. In one case the minke beached itself and died. Four attacks were successful. In one instance a subadult minke was killed in open water following a chase. In two cases the fleeing minke entered a confined bay and was killed by the killer whales. One adult minke was taken after apparently attempting to seek cover beside a large sailboat. Minke whales made no attempt to physically defend themselves and were killed by repeated ramming or by asphyxiation. Although killer whales are capable of sprinting speeds greater than those of minke whales, it appears that adult minkes can maintain higher sustained speeds and evade capture if sufficient space for an extended escape trajectory is available. Successful predation of minke whales in coastal waters is rare compared to pinnipeds and small cetaceans, the main prey of transient killer whales. [source]

Comparative hepatic activity of xenobiotic-metabolizing enzymes and concentrations of organohalogens and their hydroxylated analogues in captive greenland sledge dogs (Canis familiaris),

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2009
Jonathan Verreault
Abstract A captive study was performed with Greenland sledge dogs (Canis familiaris) fed a naturally organohalogen-contaminated diet (Greenland minke whale [Balaenoptera acutorostrata] blubber; exposed group) or a control diet (pork fat; control group). The catalytic activity of major xenobiotic-metabolizing phase I and II hepatic microsomal enzymes was assessed. Relative to control dogs, ethoxyresorufin- O -deethylase (EROD) activity in exposed dogs was twofold higher (p = 0.001). Testosterone hydroxylation yielded 6,- and 16,-hydroxy (OH) testosterone and androstenedione, with higher rates of production (23,27%; p , 0.03) in the exposed individuals. In the exposed dogs, epoxide hydrolase (EH) activity was 31% higher (p = 0.02) relative to the control dogs, whereas uridine diphosphoglucuronosyl transferase (UDPGT) activity was not different (p = 0.62). When the exposed and control dogs were combined, the summed (,) plasma concentrations of OH-polychlorinated biphenyl (PCB) congeners were predicted by plasma ,PCB concentrations and EROD activity (p , 0.04), whereas testosterone hydroxylase, EH, and UDPGT activities were not significant predictors of these concentrations. Consistent results were found for individual OH-PCB congeners and their theoretical precursor PCBs (e.g., 4-OH-CB-187 and CB-183, and 4-OH-CB-146 and CB-146) and for EROD activity. No association was found between ,OH,polybrominated diphenyl ether (PBDE) and ,PBDE plasma concentrations, or between potential precursor-metabolite pairs, and the enzyme activities. The present results suggest that liver microsomal EROD activity and plasma PCB concentrations have a greater (e.g., relative to EH activity) predictive power for the occurrence of plasma OH-PCB residues in sledge dogs. These results also suggest that plasma OH-PBDEs likely are not products of cytochrome P450-mediated transformation but, rather, are accumulated via the diet. [source]

Decreased feeding ability of a minke whale (Balaenoptera acutorostrata) with entanglement-like injuries

MARINE MAMMAL SCIENCE, Issue 3 2009
Brian W. Kot
First page of article [source]

KILLER WHALE ATTACKS ON MINKE WHALES: PREY CAPTURE AND ANTIPREDATOR TACTICS

Distribution of minke whales in the Bellingshausen and Amundsen Seas (60°W,120°W), with special reference to environmental/physiographic variables

FISHERIES OCEANOGRAPHY, Issue 3 2000
Fujio Kasamatsu
The relationship between the distribution of minke whales (Balaenoptera acutorostrata) in the Bellingshausen and Amundsen Seas (longitude between 60°W and 120°W), and environmental and physiographic variables (sea-surface temperature, sea-ice extension, and sea-floor-slope type), was studied to determine whether these environmental and physical factors affect the distribution and density of minke whales. The analysis was based on sightings data obtained from the 1989/90 and 1982/83 IWC/IDCR cruises. The mean sea-surface temperatures for comparable areas were significantly higher in 1989/90 (2.04°C) than in 1982/83 (1.12°C), and the area where the sea-surface temperature was greater than 1°C in the 1989/90 study was approximately twice that of the 1982/83 study. Additionally, during the surveys, the extent of the sea ice in 1989/90 was less than that in 1982/83, with the mean ice edge about 92.6 km (50 nautical miles; 1 nautical mile ,1.852 km) farther south in 1989/90 than in 1982/83. This is consistent with the sea ice extent observed in winter, when the sea ice extent was less in 1989 than in 1982. The distribution of minke whales was substantially different between the two surveys, with the density and abundance of minke whales being greater in 1982/83 than in 1989/90. The warmer sea-surface temperatures, fewer cold-water intrusions, and the smaller extent of sea ice in 1989/90 may be related to the difference in distribution of minke whales from 1982/83, possibly owing to the shift in availability of prey. [source]

Fishing gears involved in entanglements of minke whales (Balaenoptera acutorostrata) in the East Sea of Korea

MARINE MAMMAL SCIENCE, Issue 2 2010
Kyung-Jun Song
Abstract Entanglement of marine mammals in fishing gear is a global issue. It is considered a significant threat to minke whales (Balaenoptera acutorostrata) in the East Sea of Korea. A total of 214 entanglements of minke whales in this area between 2004 and 2007 were used to investigate types and parts of fishing gears involved in entanglements. The majority of entanglements were mainly caused by three types of fishing gears: set nets, pots, and gill nets (n= 207, 96.7%). Other entanglements were associated with bottom trawls, purse seines, and trawls. A total of 65 entanglements were attributed to the main and branch lines of fishing gears. The most common body part of minke whales which attached to fishing gears was the mouth (n= 63, 30.4%). Most entanglements took place within 10 nmi from land (n= 179, 86.5%), and between 10 and 220 m of water depth. The mean length of entangled minke whales in set nets was significantly smaller than that of whales in pots and gill nets samples (P < 0.001). Also, the mean body length of minke whales that entangled in the coastal area and shallow waters was significantly shorter than that of whales in the offshore area and deep waters (P < 0.001). This information can be used as fundamental data to conserve and manage this population of minke whales in the East Sea of Korea, and also to modify fishing gear to reduce entanglements. Future studies should focus on investigating the impact of these entanglements on the population and the effectiveness of mitigation measures to reduce entanglements of minke whales in this area. [source]

KILLER WHALE ATTACKS ON MINKE WHALES: PREY CAPTURE AND ANTIPREDATOR TACTICS

Detecting dyads of related individuals in large collections of DNA-profiles by controlling the false discovery rate

MOLECULAR ECOLOGY RESOURCES, Issue 4 2010
H. J. SKAUG
Abstract The search for pairs (dyads) of related individuals in large databases of DNA-profiles has become an increasingly important inference tool in ecology. However, the many, partly dependent, pairwise comparisons introduce statistical issues. We show that the false discovery rate (FDR) procedure is well suited to control for the proportion of false positives, i.e. dyads consisting of unrelated individuals, which under normal circumstances would have been labelled as related individuals. We verify the behaviour of the standard FDR procedure by simulation, demonstrating that the FDR procedure works satisfactory in spite of the many dependent pairwise comparisons involved in an exhaustive database screening. A computer program that implements this method is available online. In addition, we propose to implement a second stage in the procedure, in which additional independent genetic markers are used to identify the false positives. We demonstrate the application of the approach in an analysis of a DNA database consisting of 3300 individual minke whales (Balaenoptera acutorostrata) each typed at ten microsatellite loci. Applying the standard procedure with an FDR of 50% led to the identification of 74 putative dyads of 1st- or 2nd-order relatives. However, introducing the second step, which involved additional genotypes at 15 microsatellite loci, revealed that only 21 of the putative dyads can be claimed with high certainty to be true dyads. [source]

High proportion of protected minke whales sold on Japanese markets is due to illegal, unreported or unregulated exploitation

ANIMAL CONSERVATION, Issue 5 2009
V. Lukoschek
Abstract Whale meat products sold on Japanese markets originate from two stocks of North Pacific (NP) minke whales Balaenoptera acutorostrata scammoni: the depleted J-stock, which has been protected since 1986 but continues to be killed as fisheries ,bycatch', and the more abundant O-stock, which is hunted under special permit (scientific whaling). We investigated the geographic distribution and temporal changes in stock composition of NP minke whale products sold on Japanese markets between December 1997 and June 2004. From nearly 1200 ,whale meat' products purchased during this time, 250 were identified as NP minke whales by phylogenetic analysis of mitochondrial DNA (mtDNA) sequences. The 250 NP minke whale products were found to represent 201 unique ,market individuals' after exclusion of replicate products using microsatellite genotypes. Market individuals were further classified into four mtDNA haplogroups, three of which are characteristic of the J-stock (J-type) and one characteristic of the O-stock (O-type). There were moderate differences in the proportions of J-type individuals found in coastal prefectures, perhaps reflecting regional differences in the sale of local bycatch, but no significant difference across time. The absence of a change over time was inconsistent with the four- to fivefold increase in reported bycatch, from an average of 25,122 whales year,1, following a 2001 regulation allowing commercial sale of whales taken as bycatch. Using a mixed-stock analysis based on haplogroup frequencies over the entire survey period, we estimated that 46.1% (se, 4.2%) of all market individuals originated from the J-stock. This estimate of illegal, unreported or unregulated (IUU) exploitation is higher than expected from the officially reported bycatch, suggesting either large-scale under-reporting and/or unrecognized takes of J-stock minke whales from Pacific coastal waters by the scientific hunt. Our estimates of the true level of IUU exploitation have important implications for recovery of this depleted coastal stock. [source]