This past week was a shortened work week due to the Fourth of July holiday. The shortened work week, however, meant that I had even less time to practice my newly acquired and refined analytical skills. I dove into theoretical papers about proper BACI designs (Before-After- Control- Impact) and discussed its application to the goals and objectives of the Oregon Marine Reserves. I also learned how to perform a power analysis, which essentially is a prospective method for determining an appropriate sample size required to detect a significant result within a given degree of confidence. This power analysis is a critical component of any experimental design, especially those that require the lethal extraction of animals.

One of the fundamental questions surrounding Marine Reserves is determining whether or not fish species tend to be older inside reserves than outside. To answer this question, some fish need to be lethally removed for otolith extractions, which can give a relatively accurate estimation of age and sexul maturity. But how many fish need to be lethally removed? If too little are removed then it may be an insufficient sample size to render a significant result. However, if too many are removed then more fish were euthanized than necessary, the idea being to minimize fish mortality. Thus, power analysis proves critical in this way by indicating the smallest sample size needed to detect a significant change in size.

On last week’s post I discussed my experience with the PIT tagging project. There was a question regarding the relevance of PIT tagging to my work here at HMSC. Although PIT tagging was an enjoyable learning experience, it did not relate directly to my work.  I mainly took the opportunity to practice proper fish handing, weighing, and measuring techniques, which I will be performing a lot of in the next upcoming weeks. ODFW will be chartering out fishing boats where volunteer anglers will attempt to catch a wide variety of rockfish species. When a fish is caught, it will be brought on deck to be quickly identified, measured, and weighed. Most will then be released, but a small percentage will be kept for otolith extraction. Fishing will take place in marine reserves and their respective comparison areas to gather baseline data on species composition and their associated physical attributes. This baseline data is critical for proper BACI designs and will be an important component for future analysis. Next week’s blog I will discuss some preliminary results of a few analyses that I have helped in. But until then, science awaits!