March 2012

28 March. The PCCS right whale aerial team took off from Chatham airport around 10:00am and surveyed Cape Cod Bay in a north to south direction. Our survey began on the backside of Cape Cod where only one minke whale and one humpback whale were sighted. Right whales were not sighted until we reached Race Point off of Provincetown, in this area we had approximately ten animals. The right whales were sub-surface feeding or in surface active groups (SAGs). However, due to increasing winds the plane was forced to land back in Chatham after only an hour and a half of flight time.

23 March. PCCS right whale habitat program cruise SW855 was conducted in calm conditions (sea state 1), warm temperatures, and excellent visibility. The cruise was directed at zooplankton sampling needed to map the extent of the region of rich surface copepod patches that has been controlling the distribution and behavior of the right whales in the near-shore waters of Race Point and Herring Cove, Provincetown. During the cruise 15-20 right whale sightings were recorded and 77 zooplankton samples collected.

The zooplankton resource is presently spread along the steep sand face of the Herring Cove shoal and on the adjacent shallows (<10 meters), an area of strong tidally-driven, medium-scale frontal activity. The resource appears to be partitioned into disjunct patches 3-10 meters in diameter and concentrated in a 1 meter layer between 0.5 and 2 meters deep. Right whale behavior observed during SW855 was principally medium and high surface skimming at low velocity. The resource collected in path of right whales was dominated by Calanus finmarchicus copepodites (stage 4 and 5) and adults, with a strong contribution from the sub-dominant taxon Pseudocalanus ssp.

The increase in the Calanus resource, now the major contributor to the bulk volume of the right whales’ food in the northeastern quadrant of the bay, and observations of low zooplankton resources in the remainder of the bay a week ago suggest that the right whales will continue to aggregate and feed in the present location, close to the outer beaches of Provincetown. These favorable conditions may be expected to continue until strong winds, forecast for 26 March, disrupt the upper water column. Thus continued right whale aggregation and feeding activities are forecast to continue in the near shore waters along the outer beaches of Provincetown for the next 3 days. If additional enrichment by late stage Calanus over a larger area of Cape Cod Bay were to occur during the next week, as is typical of late March, an increase in right whale density and relocation into the southern reaches of the bay would be expected.

The combination of the present area of right whale concentration within the shipping lanes and near-surface feeding behavior that causes whales to swim at shallow depths elevates the risk of ship strike, the subject of a recent DMF advisory.

19 March. Habitat program cruise SW853 was directed at photo identification and at studies to identify the foraging conditions that are controlling the aggregation of right whales in the shipping lanes close to Race Point, Provincetown. Sea conditions during the cruise were calm with light winds, unlimited visibility, and moderate to warm air temperatures. Sea surface temperatures during the cruise ranged from 5.5 to 7 degrees Celsius. During the cruise 20-30 Right whales, 1 Fin whale, 2 Humpback whales, 3 Harbor porpoises, 4 Minke whales, and 50-75 White-sided dolphins were recorded, all within 3 miles of Race Point and the Herring Cove. A total of 70 zooplankton samples were collected in the vicinity of skim feeding right whales, which samples will be enumerated in order to track the quality of foraging conditions within the bay. During the cruise 3 CTD casts were made to collect vertical thermal structure, light penetration, and chlorophyll data.

Zooplankton collections made during SW852 (16 March) at regular monitoring stations deep in the south and central bay indicated the presence of a poor quality of zooplankton resource except in the vicinity of skim feeding right whales. Samples in the path of a whale at the far northeastern quadrant were the only collections on SW852 that exceeded feeding threshold. The zooplankton resource collected during SW853 similarly showed a strong zooplankton resource close to Race Point, a resource that was mapped using a horizontal pump collection system. The most concentrated patch of zooplankton was located in a restricted region approximately 4 km (north-south) by 1 km (e-w) with the greatest density at a depth of 2-3 meters, oriented along the steep sand shelf off Herring Cove and Race Point. In that location the bottom rises from approximately 55 meters to 5 meters over a horizontal distance of 75 meters. Zooplankton at the 2-3 meter depth along the shelf was estimated to exceed feeding threshold and the majority of right whales were observed in this location.

Samples collected in the path of feeding right whales showed the first indications of the calanoid species that historically has dominated feeding activity during the spring in Cape Cod Bay, Calanus finmarchicus. The zooplankton resource also included the mid-winter taxa Pseudocalanus ssp. and Centropages and other smaller taxa. The influx of Calanus, an important component of the right whale food resource, suggests a more typical pattern of resource enrichment during a season that has been unusual in many respects, and explains the pattern of aggregation and feeding that has been observed during the past week. Should it occur, further enrichment by Calanus, particularly in the southern quadrants of the bay, would likely be a harbinger of a pattern of zooplankton and whale distribution typical of late March and April. Thus, the continued aggregation of right whales, now 3 months old, may be expected if the enrichment and patch formation documented on SW853 continues. The presence of the controlling calanoid resource, in a location of strong small scale frontal activity and intense tidally driven current turbulence, has during previous seasons resulted dense feeding aggregations of relatively short duration.

The behavior of the whales and their location in the shipping lanes, along with the likelihood that these conditions will continue for several more days, increases the risk of ship strike in the area of high food density.

These observations are considered preliminary pending detailed analysis and final assessment reporting.

19 March. Bright sunny skies and calm seas greeted us as we departed from Chatham airport to survey the waters east of the cape. We began by flying from the airport and picking up our northern line to the northwest of Race Point. As we transited through the bay to our starting point we observed several groups of feeding right whales in the vicinity of Herring Cove. Just as we turned onto track we broke north to check out a diving humpback. While circling we could see a large SAG of right whales off Stellwagen Bank which we proceeded to documented. As we continued along our first line we were once again pulled north by a breaching right whale, and a bit later found the days first fin whale. The rest of the survey was quite slow for right whale sightings with two SAGing together. On an interesting note these two individuals have not been seen since this time last year, so where have they been in the interim – only they know for sure. As we continued along a possible fin whale was observed in the southwest and a busy section of sea with several humpback and fin whales in the southeast section of our survey. While on track during this survey in total we observed eleven right whales, three fin whales, five humpbacks, and many dolphins.

17 March. Today we got back up in the air after a chunk of time with our plane down due to bad weather and regularly scheduled maintenance. We were greeted early on with a pair of right whales on the back side and a few more east of Pilgrim Lake. Then as we began to survey the bay from north to south we hit the jackpot, and encountered a large group of feeding and SAGing right whales along shore of Race Point and down past Herring Cove. We observed much skim and subsurface feeding along with echelon feeing. In echelon feeding two or more whales will swim together in a tight “V” formation (much like you might see migrating birds). As we continued south through the bay the numbers of whales plummeted with only two other individuals sighted, one of them was lobtailing and so gave us a bit of a show. All told we ended the day with approximately thirty-four right whales, one fin whale, and one minke whale.

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