April 2012

17 April. The PCCS aerial team took off from Chatham airport and conducted a south to north survey of Cape Cod Bay. A total of twenty right whales were observed spread throughout the bay. Three right whales were spotted within five miles of the Cape Cod Canal, two others were spotted very close to the mouth of Plymouth harbor, and one right whale was spotted within Provincetown harbor very close to the West End breakwater. The marine traffic enforcement division of the Cape Cod Canal was alerted of our sightings near the canal so they can alert any marine traffic utilizing the canal to the presence of right whales. There were also nine minke whales, seventeen fin whales and nine humpback whales observed.

17 April. Right whale habitat program cruise SW861 was conducted in exceptional weather conditions with calm winds, a glassy sea, unlimited visibility, and air temperatures exceeding 15 degrees C. A total of 7 right, 4 fin, 5 minke whales sightings were recorded and CTD and zooplankton data were recorded at 6 regular stations; 18 zooplankton samples were collected in the vicinity of subsurface feeding whales.

The zooplankton over much of the bay as sampled on this and SW860 is now dominated by late stage copepodites of Calanus finmarchicus. Except in regions of patches, the calanoid densities appear to be of low to moderate richness. The zooplankton resource of the bay is restricted to relatively small areas scattered widely along the margins of the bay, but in those patch areas vertical sampling suggests that Calanus forms layers between 1-4 meters deep at densities that exceed the feeding threshold by an order of magnitude. Along the western side of Cape Cod Bay the disjunctive distribution of the resource appears to have moved to the west and north from the area of right whale aggregation 4 days ago to enter the eastern margin of the Cape Cod Canal – Boston shipping lane. In response to the widely dispersed resources, the whales in the western quadrants have been subsurface feeding at a depth of 2-4 meters on a resource that spans the upper water column.

We forecast a general dispersion of resource patches to the east and, eventually, north with increasing possibility of aggregation of right whales in the eastern quadrants toward which the Calanus resources will tend to move. While conditions favor coalescence of the resource and near-surface feeding activity in the eastern ½ of the bay, the wide spread distribution of the zooplankton suggests the possibility of ephemeral feeding aggregations anywhere in the bay during the next 2-3 days.

Although the present location of the Calanus resource in the western bay elevates the risk of ship strike, it is likely that the patches of calanoids will disperse and move east over the next several days, soon reducing the potential for near-surface aggregation of feeding whales in the area of greatest ship strike potential.

13 April. They’re Back…… Early in the week there were unconfirmed reports of right whales deep in the bay. Before we even got our wheels off the ground today we received a call from the Coast Guard informing us of a small group of whales outside the canal. Since we were surveying north to south, our first right whale was sighted skim feeding near Race Point. Another single was found near High Pines on the west side of the bay. Shortly after this we got a call from the R/V Selkie, an NEFSC vessel conducting right whales studies in the bay. They were with a large group of right whales and had found an entangled animal. We broke survey and headed towards their location while notifying the PCCS Marine Animal Entanglement Response Team. Once on scene we found an animal that was known to be entangled from a previous sighting earlier this season. The entangled whale was skim and subsurface feeding amongst approximately 30 other whales with the same behavior. This situation offered unique challenges, one of which was keeping track of the entangled whale amongst so many others. The plane stayed on scene and assisted the disentanglement team until it was necessary to land to refuel. Once the plane was back up the entangled whale had separated from the feeding aggregation and was easier for the disentanglement team to track, so we got back to the survey. Since we were in the southern part of the bay we picked up our southern-most trackline and began to survey south to north. As we proceeded we again encountered and documented the group of feeding right whales which had stayed primarily in the same area of the bay. The feeding now appeared to be a little less coordinated than it was earlier. We were able to complete the entire survey and additionally sighted one minke, seven fin, and five humpback whales.

13 April. PCCS right whale habitat program cruise SW860 was conducted in moderate conditions (sea state 2-3 and air temperature in the 40’s) and excellent visibility. The cruise was initially directed at zooplankton sampling to evaluate the food resource throughout the bay, which had been of poor quality during the last 10 days, concentrated at a density below that required to elicit right whale feeding. An aggregation of right whales performing surface and near surface feeding behavior was sighted by the PCCS-DMF aircraft in the far southwestern margin of the bay in the vicinity of the entrance to the Cape Cod Canal. Zooplankton was sampled in the paths and in the vicinity of the whales. During the cruise 22-26 right whale sightings were recorded and 59 zooplankton samples collected.

The zooplankton resource over the large part of the bay is low, however zooplankton densities in the vicinity of the foraging whales was estimated to be well above the feeding threshold and dominated by Calanus finmarchicus copepodites (stage 4 and 5). Through vertical and horizontal transects the main patch dimensions were estimated to be 300m (l) x 130m (w) x 4 m (d). Although the area where the strong resource signal and whales were recorded does not usually play a significant role in right whale surface feeding activities during the late winter and early spring, it appears that the essential processes that cause patch formation are acting on an increasing Calanus resource in that location, perhaps another anomaly of the 2012 season. The few observations of significant aggregations of feeding right whales in the near-shore area in the southwestern quadrant in the past suggest that, barring strong winds, the whales may remain in that area for several days and with slow movement of the controlling resource as toward the west and north. The risk to right whales of collision with shipping transiting the Cape Cod Canal is elevated and with movement further west will increase significantly. Presently the whales observed in the area of the entrance to the canal are feeding actively near surface layers of zooplankton, hence they are often difficult to spot and avoid. Because samples at regular stations throughout most of the bay contained moderate to low concentrations of the resource, it is likely that the feeding activities in the area of risk will continue for another 3-5 days and that near surface feeding will, after that period, move east along the south margin of the bay as patch formation processes are developed in the south central portion.

6 April. The PCCS aerial team took off from Chatham airport and conducted a south to north survey of Cape Cod Bay. Although a complete survey was flown, only one right whale was spotted within the bay. The whale was spotted in the middle of the bay skim and sub surface feeding. The weather was not ideal for spotting, but we are pretty confident that if there were a large number of right whales in the area they would have been noticed. So, it seems there may have been an early exodus of right whales from Cape Cod Bay. Typically, this would be very early to have all of the right whales move onto another area, however this season has been so strange in so many regards that nothing is surprising at this point. Five fin whales and two humpback whales were also observed.

4 April. Our second flight in April consisted of a north to south survey of the back side of the Cape. Our first right whales were quickly encountered as we rounded Race Point. This group was engaged in a SAG. An additional two groups and a single animal were skim and sub surface feeding along a slick that paralleled the northern shore turning down and continuing to follow the coast. As we preceded along the track lines three other right whales were cited predominately in the south central section of the survey. Of these, two were feeding and one was traveling. During today’s survey we observed a total of fourteen right whales along with an additional four minke whales, six fin whales, and eight humpback whales.

1 April. The PCCS aerial team took off from Chatham airport and conducted a north to south survey of Cape Cod Bay. A total of five right whales were observed in the bay. One right whale was observed skim feeding while the rest were traveling. We also observed ten minke whales, four fin whales and two humpback whales. Minke whales are the smallest of the baleen whales that we typically see in this area, ranging from 20-25 feet and 8-10 tons. They were named after a Norwegian whaler. Every minke whale has a white stripe on each of its pectoral flippers which is often affectionately referred to as the “Minke mittens”.

1 April. Habitat program cruise SW856 focused on photo identification and on the collection of zooplankton, phytoplankton, and oceanographic data at regular station locations in the right whale critical habitat. Sea conditions during the cruise were calm under light southerly and southeast winds, with moderate temperatures and unlimited visibility. Sea surface temperatures during the cruise ranged from 6.5 to 7.8 degrees Celsius, continuing the 2012 trend of surface temperatures significantly above the 24-year average. During the cruise 5 right whales, 3 fin whale, 9 harbor porpoises, 2 minke whales, 1 humpback whale and 10-20 white-sided dolphins were recorded. Zooplankton samples were collected at 6 regular Cape Cod Bay stations and at 2 special stations in the vicinity of right whales.

As forecast, the first zooplankton samples from Cape Cod Bay after the recent period of northerly gales showed a considerable weakening of the zooplankton signal that was particularly strong in the area of Herring Cove, Provincetown; the location where for two weeks active surface feeding by 20-30 right whales was regularly reported. Zooplankton collections made during SW856 at regular and special monitoring stations throughout the critical habitat and deep along the southern tracks document a poor quality of zooplankton resource dominated by a mix of calanoid copepods with significant contribution from pteropods in samples from stations in the northeastern bay. Midwater samples at the far northeastern station in the bay showed the highest concentration of pteropods, estimated to approach 4,000/ cubic meter, a concentration not seen in any sample collected over the last 27 years.

The zooplankton resource throughout the bay and in the vicinity of right whales was judged to be well below the densities required to elicit feeding behavior by right whales. We forecast that these relatively poor conditions will continue for much of the next week, until the small-scale transport processes that concentrate calanoids are reestablished in areas favorable to right whale aggregation and feeding. The continued presence in bay-wide samples of late larval stages of Calanus finmarchicus suggests the likelihood that re-concentration of zooplankton patches contingent on development of the frontal conditions that usually prevail in the southern and eastern quadrants during April.

The paucity of zooplankton throughout most of the bay and associated right whale behavior indicates that aggregation and surface feeding by right whales is unlikely during the next 5-7 days and that risk of ship strike and entanglement is moderately low.Â

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