Answer can be on shark or any fish. Some sharks are endothermic however. You need to know which yours is to actually make a hypothesis. Yes, but sharks normally stay in waters of approximately the same temperatures.
All heterothermic animals are dependent upon the environmental temperatures in order to operate.
The classic experiment performed in many biology classes is to adjust the temperature of a goldfish water and count its gill motions. A nice curve results. Argonne National Laboratory, Division of Educational Programs, Harold Myron, Ph.D., Division Director.