The purpose of this research was to explore the impact of finfish bycatch on the ocean shrimp Pandalus jordani fishery using two methods. One method looked at the breakage of the shrimp by finfish bycatch in the nets. The other looked at the impact of bycatch on fishing decisions. At-sea research found that finfish bycatch contributes to the breakage of ocean shrimp. However, the impact is small relative to breakage caused by other handling procedures. Bycatch was measured from each net of a double-rigged shrimp vessel, where one side employed a Nordmore grate bycatch reduction device (BRD) and the other served as a control. Shrimp catch was controlled for BRD use and catch day, and sampled throughout processing to evaluate breakage. At greater than 50% bycatch there was a significantly higher percentage of broken shrimp in the control side than in the BRD side for samples taken at the first and third sampling point (p<0.05). After this point the differences became non-significant. The percent breakage increased from a mean 2.4% broken before placement in the hold to a mean 18.0% broken in the final product. The impact of bycatch on fishing decisions was evaluated by distributing an expanded logbook to volunteer Oregon shrimp vessels in 1998. Logbook questions addressed the reasons and time involved for running to initial fishing grounds, relocating overnight, relocating between tows, dumping tows, and modifying gear. Completed logbooks were collected from 20 vessels representing 263 trips, 1043 fishing days, and 4727 tows. A soft mesh BRD was used at some point by 25% of vessels on 8.7% of trips and 3.3% of tows. Bycatch did not figure prominently in reasons given for choice of initial fishing grounds, relocating between fishing days, or relocating between tows. Bycatch was the main reason cited for dumping tows. In total, 430 (9%) tows were dumped. The estimated weight of fish and shrimp dumped equaled 11.3% and 0.3%, respectively, of the landed shrimp catch. Pacific whiting Merluccius productus caused 81.4% of the tows dumped due to bycatch. Opportunity costs attributed to bycatch alone were equivalent to net revenue resulting from 12.3 tows or $3,203 per study vessel. At the fleet level, opportunity costs due to dumped tows totaled 1,227 effort hours, 32.4 trips, or $155,070. This equates to a 4.6% loss in gross ex-vessel revenue. / Graduation date: 2002

The cave tetra (Anoptichthys jordani, now reclassified as Astyanax jordani) is a blind form of the Mexican banded tetra (Astyanax fasciatus mexicanus). It lives in the waters of underground caves in northern Mexico. In the conditions of complete darkness there, the cave tetra has gradually lost the need for eyes and colouring. The females are larger than the males and have a bulkier abdominal section. They are omnivorous, feeding on animal and plant matter. The aim of this research was to determine the influence of basic types of lighting system on the spawning and rearing of Anoptichthys jordani. The findings reveal that alternating light and dark are best used for successful spawning and rearing of this species. The ideal temperature for Anoptichthys jordani ranged from 23-24°C for breeding and from 25-26°C for spawning, with pH levels of 7-8 and a specific electrical conductivity of approx. 230 ?S/cm, and with dissolved oxygen levels in the water of approx. 8.00 mg/L. The monitoring required for compilation of the research project was performed in the aquarium room at the Department of Biological Sciences from February 2013 to March 2014. Fish aged approximately 1-3 years were used for the reproduction. The separated males and females were placed in spawning tanks at regular intervals, always in single pairs. The same experiment was conducted in parallel in conditions of light and absolute darkness. A WTW meter was used for measurement of the water values.

Over the last 3 decades, freshwater aquaculture has become one of the most important food industries. However the constant introduction of a reduced number of very successful species for aquaculture has been identified as one of the main activities related to the alarming decline of fish biodiversity worldwide. This issue has raised awareness amongst the scientific community, governmental authorities and the general public towards freshwater fish biodiversity. This new awareness has promoted the development of “green” markets and environmentally friendly strategies, aiming for a reliable production of protein sources. The development of native species aquaculture has been presented as a strong alternative for sustainable aquaculture and the protection of biodiversity. However, it seems clear that unplanned native species aquaculture developments can be as detrimental on local biodiversity as the introduction of exotic fish, if not more dangerous. Therefore, the advantages and disadvantages of native species aquaculture have to be clearly analysed before any aquaculture development. This study aimed to establish a philosophical background regarding the use of native fish species in aquaculture in contrast to the introduction of exotic species that may compete for a similar niche as food in local markets. The main ecological impacts that exotic fish species may have on natives, such as competition, predation, and hybridization were discussed. In addition, a well planned native species Aquaculture Strategy for the Protection of Biodiversity was produced, at catchment level, within a Geographic Information System (GIS). For the development of the native species aquaculture strategy in central Mexico, four species of Atherinids (Chirostoma estor, C. Jordani, C. promelas and Atherinella balsana) and two species of native Ictalurids (Ictalurus balsanus and Ictalurus dugesii) were included in this study. These six species are relatively new to aquaculture and they were selected on the basis of their importance in local fisheries and markets in their native basins of the Lerma-Santiago and Balsas rivers. Both of these basins are of great importance in central Mexico, not only because of their biodiversity but also because of their high human population densities and socio-economic status. The use of Geographic Information Systems was a fundamental factor in the development of the native species aquaculture strategy at catchment level, consisting of site suitability models (SSM) for each species in their corresponding native catchments. Overall, SSM identified 13,916 km2 and 11,178 km2 highly suitable for aquaculture of the studied Atherinids and Ictalurids respectively, based on Water, Soil and Terrain, Infrastructure and Risk sub-models. A set of predictive species distribution models (PSDM), which related ecological characteristics for each studied species with relevant environmental and topographic parameters into a GIS, were also produced. Such models were developed for the establishment of potential natural ranges of distribution for each species, as well as their potential to become exotic in new environments, as a potential for invasion model (PI). Based on a partial verification, both PSDM and PI models produced results that were satisfactorily consistent with the known distribution of each modelled species. The combination of SSM and PSDM produced an Aquaculture Strategy for the Protection of Biodiversity model (ASPB) which identified the most environmentally friendly suitable areas for aquaculture sites. In contrast, the combination of the SSM with PI models into an ASPB model identified the site suitability potential for non-native species that are genetically close to native ones, in an attempt to reduce the known impacts that exotic species have on local biodiversity. In this way the ASPB model identified 7,651 km2 suitable for aquaculture of I. balsanus in its native Balsas basin and 15,633 km¬2 suitable for aquaculture of the non-native I. dugesii. ASPB models were produced for all the studied species. The final results were used to produce a set of guidelines for the development of sustainable aquaculture of native species at catchment level that cover genetic and ecological implications, as well as a well planned decision making tool produced in a GIS.