Research Question

The Pacific Coast Feeding Group (PCFG) is a subgroup of the Eastern North Pacific (ENP) population of gray whales (Scordino et al.2018). The ENP, a population of 24,000-26,000 individuals, migrates along the U.S. west coast from breeding grounds in the lagoons of Baja California, Mexico to feeding grounds in the Bering Sea (Omura 1988). The PCFG, currently estimated at 264 individuals (Calambokidis et al.2017), stray from this norm and do not complete the full migration, instead choosing to spend their summer feeding months along the Pacific Northwest coast (Scordino et al.2011). Since gray whales as a species already exhibit specialization (by being the only baleen whale that benthically forages) and since the PCFG display a second tier of specialization by not using the Bering Sea feeding grounds, it seems plausible that individuals within the PCFG might have individual foraging specializations and preferences. Therefore, my research aims to investigate whether individual gray whales in Port Orford exhibit individual foraging specializations. Individual foraging specializations can occur in a number of different ways including habitat type (rocky reef vs sand/soft sediment), distance to kelp, time and distance of foraging bouts, and prey type and density. For this class, my research question is whether prey species drives the amount of time a foraging whale will spend at a specific foraging location.

Data

Prey data

The prey data has been obtained through zooplankton tow net samples from a research kayak in the summers of 2016, 2017 and 2018. Kayak sampling effort varies widely between the three years due to weather creating unsafe conditions for the team to collect samples. These samples have been sorted and enumerated to the zooplankton species level so that for each day when a prey sample was collected, we have known absolute abundances of prey species at each sampling station.

Whale data

The whale data is in the form of theodolite tracklines of gray whales that used the Port Orford study area during the summers of 2016, 2017 and 2018. Since whale tracking occurs at the same sites as prey sampling, we are able to map the prey community present at a particular location that whales forage at. The tracklines occur on a very fine spatial resolution as the study area is approximately 2.5 km in diameter, though some of the tracklines extend out to approximately 8 km offshore. Furthermore, as whales forage in the area, photographs are taken of each individual in order to match the trackline with a particular individual. This way, potential individual specializations may be detected if there are repeat tracklines of an individual.

Hypotheses

There will be differences in time spent by individual gray whales foraging in an areas with different prey communities. However, these differences will likely not be constant/stable over time. Most likely, foraging will be largely driven by availability of prey and therefore individual whales will be rather flexible in their foraging strategies.

Approaches

Individual patterns in time and space use within the Port Orford study area will be assessed through the identification of foraging bouts. Theodolite tracks from 2016-2018 longer than one hour will be included in this analysis. Using ArcGIS, tracklines will be clipped so that only foraging points within the study sites are included in this analysis. Radii will be created around each of the 12 zooplankton sampling locations to identify overlap between whale foraging and known prey communities at sampling stations. Time spent within these radii will be calculated. Statistical analyses (likely GAMs) will be run in order to identify whether individuals spend more and/or less time at a foraging location based on the prey species that are present at that location.

Expected Outcomes

This analysis will likely result in plots of time spent at a foraging locations against abundance of different prey species, which will be based on the results of the statistical analyses. This will allow the comparison of whether individual whales have preferences for different kinds of prey species. Maps might also be very nice to visualize the movements of whales however I am unsure how the time element of foraging bouts could be incorporated into this (perhaps with shading of color?).

Significance

This spatial problem is important to science since genetic evidence suggests that there are significant differences in mtDNA between the ENP and PCFG (Frasier et al.2011; Lang et al.2014), and therefore it has been recommended that the PCFG should be recognized as being demographically independent. In the face of a proposed resumption of the Makah gray whale hunt as well as increased anthropogenic coastal use, there is a strong need to better understand the distribution and foraging ecology of the PCFG. This subgroup has an important economic value to many coastal PNW towns as many tourists are interested in seeing the gray whales. Therefore, understanding what drives their distribution and foraging habits will allow us to properly manage the areas where they prefer to forage.

Proficiencies

I have novice/working knowledge of Arc-Info and Modelbuilder. I have never used Python before. I have working knowledge of R and am proficient in image processing.

Literature Cited

Calambokidis, J. C., Laake, J. L. and A. Pérez. 2017. Updated analysis of abundance and population structure of seasonal gray whales in the Pacific Northwest, 1996-2015. Draft Document for EIS.

Frasier, T. R., Koroscil, S. M., White, B. N. and J. D. Darling. 2011. Assessment of population substructure in relation to summer feeding ground use in the eastern North Pacific gray whale. Endangered Species Research 14:39-48.

Lang, A. R., Calambokidis, J. C., Scordino, J., Pease, V. L., Klimek, A., Burkanov, V. N., Gearin, P., Litovka, D. I., Robertson, K. M., Mate, B. R., Jacobsen, J. K. and B. L. Taylor. 2014. Assessment of genetic structure among eastern North Pacific gray whales on their feeding grounds. Marine Mammal Science 30(4):1473-1493.

Omura, H. 1988. Distribution and migration of the Western Pacific stock of the gray whale. The Scientific Reports of the Whales Research Institute 39:1-9.

Scordino, J., Bickham, J., Brandon, J. and A. Akmajian. 2011. What is the PCFG? A review of available information. Paper SC/63/AWMP1 submitted to the International Whaling Commission Scientific Committee.

Scordino, J., Weller, D., Reeves, R., Burnham, R., Allyn, L., Goddard-Codding, C., Brandon, J., Willoughby, A., Lui, A., Lang, A., Mate, B., Akmajian, A., Szaniszlo, W. and L. Irvine. 2018. Report of gray whale implementation review coordination call on 5 December 2018.