Woods Hole Oceanographic Institution
Woods Hole, MA 02543
MERRICK, RICHARD /NMFS EASC Route: F/NEC42
SILBER, GREGORY /NMFS HQTR Route: F/PR2
CLAPHAM, PHILLIP / NMFS EASC Route: F/NEC42
The northwest Atlantic right whale population is highly endangered , comprising less than three hundred individuals . Models of population survival and reproductive rates indicate an appreciable decline in recent years (IWC, 2001). The population has a markedly low rate of increase , 1 % (Caswell et al., 1999 ), in contrast to the 7-8% increase of the southern hemisphere right whale populations (Best et al., 2001 Payne et a1.,1990). High mortality from ship strikes and fishing gear entanglements affect the low rate of increase in the northwest Atlantic population (Knowlton and Kraus , 2001). However, these two sources of mortality only account for one half of the recruitment shortfall. Evidence suggests that the shortfall may also be affected by decreased fecundity . The reproductive rate is about half that of the southern populations (Kraus et al., 2001) and the calving interval is greater in the northwest Atlantic (>Syears; Kraus et al., 2001 ) than in the southeast Atlantic (3 years ; Best et al., 2001). In addition, a 1.4-fold increase in the calving interval over a period of twenty years has been observed by two different studies (Cooke and Glinka , 1999; Kraus et al., 2001). Finally, stage structured demographic analysis indicates that the declining survival and population growth trends are primarily due to the declining survival rate of calving females (Fujiwara and Caswell 2001).
Inbreeding , disease , toxic chemical exposure and body condition associated with inadequate nutrition may influence reduced fecundity . In terrestrial mammals fertility is
impacted by an insufficiency of body fat (Frisch, 1984; Marshall and Hammond, 1926; Thomas, 1990). Likewise, in the Northeast Atlantic fin whale , Balaenoptera physalus, improved body fat condition due to increased food supply appeared to be associated with increased fecundity (Lockyer, 1986). Therefore , it is important to determine if body condition is an important factor in the reproductive failure of the North Atlantic right whale.
It is unknown whether the measurement of blubber thickness is an adequate assessment of right whale body condition. Tormosov et al., 1998 found no seasonal differences in blubber thickness in southern right whales. It is possible that the lipid content of blubber changes before any changes in blubber thickness can be detected. In addition, Lockyer et a1.,1985 discovered that an increase in blubber thickness in fin whales was not sufficient to account for the tremendous increase in body girth and thus proposed that increases in body fat in muscle and around visceral organs most likely cause increases in body girth. Therefore, we must establish an acoustic assessment of blubber lipid content and establish a more complete body condition index that includes girth, length and lipid content and thickness of blubber.
The highly successful 2000/2001 reproductive season (December 00 - March O l ), with 31 calves born (Conger et al. 2001), vs. a mean of 11.32 for the years 1980 through 1998 (Kraus et al. 2001), may have been the result of the improvement in body condition described below. This would further implicate the importance of a nutritional factor in determining reproductive success.
During this project we assessed right whale body condition acoustically by measuring blubber thickness with amplitude-mode ultrasound (Moore et al., 2001). A 0.5 MHz
transducer on a cantilevered 12m carbon fiber pole is deployed to briefly touch the dorsal aspect of surfacing right whales. The ultrasound receives an acoustic echo from the subdermal connective tissue sheath at the blubber-muscle interface and graphically displays blubber thickness (Moore et al., 2001). The figures below illustrate our progress in this ongoing project, currently funded by the Northeast Consortium.
Concurrent photo-identification of individual animals allows correlation of blubber thickness with catalogued biological data, such as gender, age and reproductive history.
At the same time, overhead stereo video footage allows measurements of length and girth.
Analysis of these blubber thickness records has shown evidence of the declining northern right whales having significantly less blubber than the more successful southern right whales. Continuation of our fieldwork, along with data generation on length and girth of the same animals will allow an in depth test of the hypothesis that these parameters are related to reproductive success in right whales. Before we can adequately test our hypothesis we need a longer series of data from northern right whales.
Acoustic blubber thickness measurement of an E. glacialis adult female. The measurement was taken on 11 Aug 99 at 14:37 hours in the Bay of Fundy. Left-hand arrow shows where the ultrasound transducer makes contact with the skin. Right-hand arrow indicates sound echo from the subdermal connective tissue sheath at the blubbermuscle interface. Range on this echogram is 31 cm. Blubber thickness is 21.7 cm.
Fieldwork in South Africa was completed as proposed, top portion of table 2. The dates of the field period differ from those originally proposed because we wanted to obtain measurements from cows during the latter part of the early lactation season. The bottom portion of table 2 summarizes the field events of the 1999 season in South Africa, prior to year one of the NMFS/CICOR project.
Body length measurements
A 2-D computer-based photogrammetric analysis is being carried out on video footage of North Atlantic right whales, obtained from fieldwork conducted in 1999 and 2001. This process consists of four main parts namely, digitising and frame grabbing ;lens unbarrelling; image transformation; and the acquisition of measurement data. Digital, time-coded video footage is reviewed and assessed for usability . Acceptable segments of the video footage are edited and saved as shorter clips using Media 1001 version 3.0, Macintosh compatible , software. Consecutive frames of individual whales, in which the whales head and base of fluke notch are both visible, are selected/grabbed and saved in Quicktime format , using Media 1001 . In order to increase the quality and definition of the images , the frames are opened using IP LabSpectrum (Macintosh version) and colour filtered using a linear filter.
The Andromeda software lens filter called LensDoc is accessible as an Adobe Photoshop (version 5.02} plug-in. LensDoc enables the user to cancel out the barrelling applied to images by various camera lenses. Calibration grids are used to help with the selection of points required when making use of the LensDoc software. LensDoc settings are applied to calibration images (containing known-size objects) which then undergo various sets of user-defined transformations , using the transformation tool found in Adobe Photoshop. Once the correct set of transformations has been determined , the whale images are run through the LensDoc unbarrelling process , followed by the determined Adobe Photoshop image transformations . After being transformed , the images are saved in .tiff format and are ready for measuring. V^hale lengths (tip of bonnet callosity to base of fluke notch) are measured using IP LabSpectrum software on a 1: l pixel basis.
Progress to date:
Approximately 3b hours of digital video footage has been reviewed and assessed for usability . An estimated 850 individual frames have been grabbed and filtered . LensDoc settings for the 1999 calibration grid has been determined, while the 2001 settings are currently being determined . Multiple transformations (using the Adobe photoshop transformation tools) for the 1999/2001 data are presently being tested. The reproducibility ofpoint selection , by making use of x-y co-ordinates, using IP LabSpectrum is also currently being assessed. Jonathan Howland (VVHOI) has written a 3-D photogrammetric programme using Matlab software. His programme makes use of filtered frames described above and is currently being tested.
This project is evolving in to a long term monitor of right whale body condition. We have learnt that northern right whales are significantly thinner than southern right whales, that right whale cows loose blubber thickness during suckling, and that they need to restore that lost blubber prior to calving anew. Thus we have developed a very important tool to assess the role of body condition, which probably serves as a proxy for recent habitat quality. The practicalities of gathering these data in the field and reducing them in the laboratory have proved to be extremely labor intensive. Thus our data analyses are ongoing with current funding. Our original proposal included the aim of studying molecular aspects of right whale reproduction by evaluating the expression of the leptin protein. To date our efforts in this regard have not borne fruit. In spite of this we are pleased with our progress and anticipate a major series of publications based on the above data, along with other data currently under process.
References : (including talks and papers)
1) Published Paper (attached as file P301-309) Ultrasonic measurement of blubber thickness in right whales M.J. Moore , C.A. Miller, M.S. Morss, R. Arthur, W.A, Lange, K.G. Prada, M.K. Marx and E.A. Frey J. CETACEANRES. MANAGE. (SPECIAL ISSUE) 2, 301-309, 2001
2) Platform Presentation Acoustic measurements of Blubber thickness vs. age, sex and reproductive history in free-ranging northern right whales C.A.Miller, M.S.Morss, M. Marx, and M. Moore 13th Biennial Conference on the Biology of Marine Mammals - Wailea, Maui, HI USA Nov 28 -Dec 31999
3) Blubber thickness and Reproductive Success in Right Whales Miller CA, Reeb, D, Best, PB, and Moore MJ 14th Biennial. Conference on the Biology Of marine Mammals , Vancouver, Canada Nov 28 to Dec 3 2001 Second Prize to first author for Student poster presentation.
4) Presentations also made each year at the Fall Right Whale Consortium Meeting at the New England Aquarium in Boston.