In 2004, the right whale surveillance program for the Commonwealth of Massachusetts Division of Marine Fisheries (DMF) was conducted in Cape Cod Bay and adjacent waters from 1 January through 15 May by the right whale research team at the Provincetown Center for Coastal Studies (PCCS). The program included bi-weekly aerial surveys and weekly habitat sampling. Collaborative efforts were conducted with researchers at Cornell University on passive acoustic sampling with bottom-mounted hydrophones deployed throughout the season from 14 December through 31 May.
The right whale research team was prepared to survey for 136 days between 1 January and 15 May 2004. Right whales were determined to be present in Cape Cod Bay for 90 days, from 10 February through 10 May. In 2004, a total of 367 right whale sightings were recorded from all platforms, of which 297 were photographed. Of those 297 photographed sightings, 296 were in Cape Cod Bay, and 1 was in an area east of the Cape. To date, 263 (89%) of the photographed sightings have been matched to 55 known right whales. These results are preliminary because most of the matches have yet to receive final confirmation. There was a minimum of 54 different right whales identified in Cape Cod Bay, and one outside of Cape Cod Bay. Photo analysis is still underway to match the remainder.
Upon completion of each survey, all sightings were reported to the NOAA Fisheries Sighting Advisory System (SAS) and the US Army Corps of Engineers Cape Cod Canal Field Station. Based on late season sightings, DMF issued an advisory to mariners extending the fishing gear modifications for 15 days beyond 30 April and a request for boaters to slow down and post a lookout when traveling in Cape Cod Bay.
Three previously entangled whales were sighted during the 2004 season; an updated assessment is presented of the condition of two whales that have been entangled since 2002 (#s 1424 and 2320) and one whale now free of gear (# 2240).
The spatiotemporal distribution and demographic profile of right whales in Cape Cod Bay in 2004 more closely resembled observations during the first four years of this study than in 2002 or 2003. A late-season scattered distribution of right whales just north of Provincetown was reminiscent of the near-shore aggregations of feeding whales seen northeast of Provincetown in 2002 and a few miles east of Cape Cod in 2003. Sightings of large numbers of feeding whales in waters on the fringes of or immediately adjacent to the Bay, particularly when food resource levels within the Bay appear high as occurred in 2004, are indications that high-quality patches of food resource can develop close to the Bay and at the periphery of the area normally surveyed and sampled.
In 2004, the right whale habitat sampling team was ready to cruise aboard the R/V Shearwater in Cape Cod Bay for the 136-day field season from 1 January through 15 May. Twenty-one cruises were completed between 4 January and 11 May, totaling nearly 150 hours at sea. Despite the exceptionally cold 2004 winter conditions that caused ice buildup on equipment, and sea ice cover in Provincetown Harbor and Cape Cod Bay during several cruises, a total of 726 zooplankton and phytoplankton samples were collected, and 136 oceanographic depth profiles were recorded.
The technique developed in 2003, using four parameters of zooplankton richness to predict the occurrence, aggregation, and residency of right whales in Cape Cod Bay, was continued in 2004. Eight stations located throughout the bay were selected and sampled on every cruise (weather permitting) to maintain a baseline data set. Data, graphics and written assessments from every cruise were sent out within a few days via an e-mail distribution list to an increasing number of interested academic, governmental, scientific, and management agencies and individuals for the purposes of aiding effective management of right whales within the Cape Cod Bay Critical Habitat. Additionally, faxes detailing cruise duration, sampling locations and types, opportunistic sightings of fishing gear, and marine mammal sightings were sent to Division of Marine Fisheries state biologists immediately following every cruise. This continually evolving habitat assessment technique repeatedly demonstrated its utility of explaining the movements of right whales, often in a predictive capacity.
A preliminary effort to compare zooplankton abundance with aerial survey sightings of right whales generally demonstrated the value of combining the two principal data sets of the project. The combined plots permit a comparison of the data that informs the DMF in their development of management actions for Cape Cod Bay. The contoured zooplankton density and whale distribution plots will be integrated in the assessment reporting of 2005 after every cruise in order to present a more robust and usable management report.
The comparative plots offer some insights into the influence of the zooplankton resource on whale distribution. The long-held view that the zooplankton resource in the eastern two thirds of the Critical Habitat is a controlling factor of whale presence in the eastern bay is supported by the comparisons presented. The comparisons also show that the zooplankton sampling methods used in 2004 do not fully capture the controlling influence of the food resource, failing to fully represent the importance of deep layers of plankton that may contribute to the aggregation of whales. Future assessment and surveillance of the Cape Cod Bay habitat will be founded on new techniques that present a more synoptic and detailed view of the zooplankton resource in order to provide a more accurate prediction of whale occurrence.
To improve the quality of the predictions that are regularly made available to DMF, future work will include the building of a small-scale predictive model that will increase the power of the assessment methods used in the Cape Cod Bay Critical Habitat.
