— Written by Ara Yazaryan

Counting dorsal rays of a rockfish

As a research assistant in the Caselle laboratory, my entire experience revolves around fish. My day starts at 9 o’clock, when I report to the lab and march over to the microscope for duty. One of the ongoing projects in the Caselle lab which I have the good fortune to partake in is the SMURF monitoring program at Santa Cruz island. The SMURF discussed here, contrary to the little blue people that may come to mind, is a large black “cushion” of intertwined black fencing material. SMURF stands for Standard Monitoring Unity for the Recruitment of Fishes. This large object is meant to mimic kelp structure, and gives planktonic fish larvae a place to settle and grow. Every two weeks, these SMURFs are netted and the fish are collected and frozen for later study. And this is where my abilities with a microscope come in! One of my primary laboratory responsibilities is to count and sort the SMURF fishes into each respective species. Though some species, such as Cabezon (Scorpaenichthys marmoratus) are instantly recognizable, other families of fish, such as juvenile rockfish (Sebastes) and the Clinids require a closer look. In order to separate them into the respective species, all rockfish must be observed under a dissecting microscope in order to count their fin rays. Each species of rockfish has a unique combination of dorsal and anal fin rays, serving to identify these individuals when they are young and have not yet developed their respective mature morphological features. I examine these fish one-by-one and sort them, and then place them into a final freezer storage.

Otoliths – note the concentric ring structure

When my eyes need a break from the microscope, I move on to fish dissections. Another of my laboratory responsibilities is extracting the otoliths from fish heads. After opening the brain case, these “ear-stones” are extracted and saved for storage. Eventually, the otoliths will be polished and observed under a microscope. As a fish mature, information about what it eats, rates of growth, and potential environmental stressors is stored inside their otoliths. All this important information can be gleaned by extracting and observing the otoliths.

Large Male Sheephead (Semicossyphus pulcher) collected at Anacapa Island

The third project that I have just begun to work with is the monitoring of California Sheephead (Semicossyphus pulcher) stomach contents between sites at Anacapa Island. Fish were captured by spear or hook-and-line (much to my inner angler’s delight) and their stomach contents will be examined to determine how MPAs affect their feeding habits and population levels. The overarching goal of these three projects, and the information I aspire most to learn about, is how California fish communities are responding to Global Change. Fishing, climate-change, Ocean warming and acidification, and pollution all have the potential to degrade our rich fish stocks. By studying and monitoring these fish, I hope to gain a better understanding of California’s complex marine ecosystems. In particular, I want to more thoroughly understand how MPAs conserve fish populations, and correspondingly alter dietary structures. I will use the Sheephead (As Dr. Caselle has made very clear, there is no “s” in the middle) as a model organism for this experimentation. I seek to answer the question: Does dietary composition of Sheephead change inside and outside of Marine Protected Areas? Using observation of stomach contents coupled with statistical quantification, I set out to answer this question over the course of my REU program. Though only two weeks have gone by, I feel as if I have gained a year’s worth of scientific immersion. Between lab work, field research, and peer camaraderie, I have gained a much clearer understanding of what research in the marine science field consists of. I look forward to what is to come, and am excited to examine many more fish in the upcoming weeks at UCSB.