Vol. 32, No. 9
September 2012
MIT students launch automatous underwater vehicle.During the Ketchikan SeaGlide Summer Camp last month, Marine Advisory agent Gary Freitag hosted campers at the OceansAlaska Marine Science Center and helped test a student-built underwater vehicle.
Sponsored by STEMAK.org, a program of the Juneau Economic Development Council, the camp was attended by 18 Ketchikan students in grades 7–9 and several Alaska teachers. U.S. Navy engineers and Massachusetts Institute of Technology undergraduates taught the students and teachers how to build gliders. The National Defense Education Program and the Naval Surface Warfare Center funded SeaGlide, and Juneau educator Bob Vieth coordinated the camp.
Campers constructed and pool-tested small automatous underwater vehicles (AUVs) from bottles, using a variety of skills including soldering, circuitry, and principles of hydrodynamics.
Four MIT physics students brought an AUV to the camp that they had built in the laboratory, to test in the clear deep southeast Alaska waters. As they launched the AUV, Freitag “chased” it with OceansAlaska’s remotely operated underwater vehicle (ROV) equipped with a video camera. The MIT students cheered as everyone watched the real-time video of their successfully navigating AUV.
The campers also toured the U.S. Navy’s Southeast Alaska Acoustic Measurement Facility, and OceansAlaska where they learned about mariculture science. Freitag is president of the OceansAlaska board of directors.
The grade 8 teaching activity, Changes in Our Local Environment, part of Alaska Sea Grant's Alaska Seas and Rivers online curriculum, was selected as a Climate Literacy and Energy Awareness Network (CLEAN) resource. In all, two teaching activities in Alaska Seas and Rivers have been selected for this honor. Funded by the National Science Foundation, the award recognizes the highest quality programs after a rigorous review by climate scientists and educators. Only 480 resources were selected from 15,000.
“Changes in Our Local Environment” guides students as they interview elders and compare old landscape photos to present vistas. During the development of Alaska Seas and Rivers, Alaska Sea Grant marine education specialist Marilyn Sigman provided substantial writing and editorial support for grade 8 investigations.
Steller sea lions are not new to the northern Bering Sea, but they seem to be making seasonal visits later than normal, according to Nome-based Alaska Sea Grant Marine Advisory agent Gay Sheffield. Sheffield is working with the Alaska Department of Fish and Game Steller Sea Lion Program and the community of Gambell in responding to local observations of new uses by Steller sea lions. Photographic documentation of sea lions that were branded when they were young, by U.S. and Russian scientists, also is providing new data on the species' distribution. Sheffield said the surveys and interactions with locals are part of a continuing U.S.–Russian collaboration.
Alaska snow crab.Marine fisheries stocks occasionally undergo abrupt shifts in response to fishing pressure, short-term environmental changes, and other unknown causes. These shifts can have devastating social and economic effects on fishing-dependent communities, but no technique exists to predict these events.
Studies of existing data show that collapse of fish stocks and commercial catches is often preceded by an increase in the amplitude of annual population variability. Detecting increasing variance and the use of other statistical indicators may provide early warning of impending shifts in ecosystems and populations, but there has been little testing of these promising tools using real world data.
Alaska Sea Grant–funded researchers Michael Litzow, of the Farallon Institute, and Franz Mueter, University of Alaska Fairbanks School of Fisheries and Ocean Sciences, studied variance tracking as a tool to detect fisheries changes, using data from several Alaska commercial fisheries known to have declined or collapsed. They analyzed catch and survey records from the Bering Sea snow crab and St. Matthew Island blue king crab fisheries, among others, to test the variance tracking approach.
The research validated variance tracking as a potentially viable tool to predict fisheries collapse. Litzow and Mueter found that variability in catch increased prior to fisheries collapses in Alaska crustacean fisheries. And they found that increasing variability could be detected up to five years before a collapse. Collapsing and non-collapsing fisheries had statistically significant differences in variability trends, showing that it is unlikely that non-collapsing fisheries would be mistaken as in danger of collapse.
Variability among vessels in catch and catch-per-unit-effort (CPUE) did not increase prior to collapse, as researchers expected. Rather fishermen continued to make consistent, though smaller, catches. This finding is important, researchers say, because it suggests that vessel fleet–scale parameters are not good early indicators of impending collapse. Long after a fishery collapsed, researchers continued to detect increased variability, indicating long recovery time for some stocks.
Litzow and Mueter showed that this method could hindcast the collapse of a fishery up to five years before it actually closed, a finding that, if further validated, could become an important forecast tool for major fisheries. These research results were included in the 2012 annual Stock Assessment and Fisheries Evaluation report for the North Pacific Fishery Management Council.