Worked on classifying skate egg cases and participated in the Eastern Bering Sea groundfish survey.
There are currently 14 species of these benthic creatures known to inhabit the Gulf of Alaska, Aleutian Islands, and Bering Sea. All skates are oviparous, meaning females deposit leathery egg cases which sometimes are referred to as “mermaid’s purses.” Each species produces a unique egg case distinguishable in size and texture from other species. Sometimes differences between species can be very slight and difficult to identify.
Using an electric calibrator I took measurements on hundreds of preserved egg cases from the different species. With data on the case length, case width, anterior horn width, posterior horn width, shell condition, and the number of ribs per centimeter on the dorsal surface for each species, I was able to compile a data base. By adding latitude and longitude coordinates for each egg case I geo-referenced the data and imported it into GIS. In GIS single species could be selected and trends could be observed. I found that several species like Bathyraja taranetzi occurred in different sizes in different areas. This could indicate that what we considered one species of skate might be in fact two different species.
I also used a high resolution microscopic camera to take digital pictures of the dorsal surface of the different species. Under high magnification the ribs or spines of an egg case become very clear and distinct. Some species have long and pointed spines while others have short and jagged ones. The pictures will also help tell species of skates egg cases apart.
Bathyraja interupta skate cases in the lab.
A microscopic photo taken of a cross section of a Bathyraja aleutica egg case.
Skates caught during the Slope Survey.
The final part of my internship with NOAA took place out on the Bering Sea for four weeks. I joined a team of scientists for the RACE Slope Survey 2010. On a chartered fishing vessel we hauled in hundreds of fish a day to weigh, sex, and length. I saw 9 of the 14 species of skates along with countless other species of fish and invertebrates.