Predictions for Hypothesis 2:
I believe that my hypothesis will hold true due to the interactions between the two types of whales and their prey. I think that if the transient population increases which decreases its prey population (pinnepids), that the populations of salmon will go up and lead to an increase in the population of resident killer whales. The opposite reaction will hold true if the transient population decreases, leading to an increase in pinnepids and decrease in salmon. The result will be a loss of resident killer whales.
Baird, Robin W., Abrams, Peter A., and Dill, Lawrence M. 1991. Possible indirect interactions between transient and resident killer whales: implications for the evolution of foraging specializations in the genus Orcinus. Oecologia. 89(1): 125-132
I managed to find a similar study that supported my hypothesis about the interactions between transient and residents through their prey’s interactions. Baird et al, 1991 did an analysis of the possibility of this topic, but as far as I can find there has been little studies actually done to test this hypothesis.
Summary of the article
There were a lot of assumptions made in this article, as there was no physical fieldwork done. It basically describes the relationships between the food webs of transient and resident killer whales. The diagram below shows this. Model A shows that residents and pinnipeds are direct competitors for the same food source and each would have a negative effect on the others population size. Model B shows that resident whales and pinnipeds have a more indirect interaction, through the fact that pinnepids eat the same prey as salmon which are the primary food of residents. This would mean that pinnepids would indirectly reduce salmon populations and hence reduce food for resident whales.
