Artificial atmosphere control system

Two-gas control system has been developed which uses existing hardware. Three systems are used for control, monitoring, and safety backup. Pure oxygen will be supplied to maintain safe pressure level should something go wrong

Evaluating potential age structures for three Alaska crustacean species

Thesis (M.S.) University of Alaska Fairbanks, 2019Banding patterns are observed in calcified structures of red king crab (Paralithodes camtschaticus), snowcrab (Chionoecetes opilio), and spot shrimp (Pandalus platyceros). Recent research supports an age determination method based on these banding patterns; however, processing methodologies for these structures have not been established. Further, species-specific evidence is needed to determine whether these patterns indicate actual age or growth. The objectives of this thesis are to: (1) describe optimal species-specific methods for producing and evaluating band counts for red king crab, snow crab, and spot shrimp; and (2) use differences in shell condition to test whether band counts indicate age for snow crab. For each species, we comprehensively thin-sectioned structures, evaluated each section for banding pattern presence (readability), and developed band count criteria. To address objective 1, we used generalized additive models to describe readability across structures to find the location that optimizes the production of readable sections. For objective 2, we used a one-way ANOVA to compare band count and endocuticle measurements among shell conditions in snow crab. Results indicated preferred structures, locations, section orientation, and thickness. Results also indicated that there is no relationship between band count and shell condition for terminally molted snow crab. These results describe optimal methods for processing crustacean structures and suggest that the potential age structures may not continue to produce bands after terminal molt in the case of snow crab. Further evaluation is needed to validate potential age relationships and the use of this technique for age estimation.the North Pacific Research Board; the Saltonstall-Kennedy Grant Award; the Alaska Department of Fish and Game; the Bering Sea Fisheries Research Foundation; and the University of AlaskaChapter 1: Development of procedures for sectioning calcified hard parts as potential age structures for three Alaska crustacean species -- Chapter 2: Evaluation of a direct age determination method for terminally molted male snow crab Chionoecetes opilio (J.C. Fabricius 1788)