It’s a Trap! Unravelling Reversible Charge Trapping in Nanocrystals Through Single Particle and Ensemble Studies

Thesis (Ph.D.)--University of Washington, 2016-08

Catch and effort from a recreational trolling fishery in a large lake

Over recent decades recreational fisheries have grown substantially throughout the world. Despite this increase, catches from recreational fisheries have often been ignored in fisheries management, although this is now being remedied. Monitoring recreational fisheries can be expensive, and the primary means used for monitoring is angler (creel) surveys, typically funded from sales of fishing licences. The studies presented in this thesis examine different approaches to monitoring recreational trolling fisheries’ catch and effort, where fishing licenses are not required and there are no reporting requirements. I present results from a complemented roving/mail-in survey undertaken during 2013-2014 to estimate recreational effort and catch of Atlantic salmon (Salmo salar) and brown trout (S. trutta) in the largest lake in the European Union, Lake Vänern, Sweden. I also evaluate different angler catch reporting methods (mail-in, tournament reports and face-to-face interviews) and compare catch rates within and among spring and fall fishing periods. In addition, mail-in survey data are examined for recall bias.   I estimate that 28.7 tonnes of salmon and trout combined were harvested by the recreational trolling fishery in 2014, more than the commercial and subsistence fisheries combined. Seasonal differences in both recreational effort and catch were observed. Effort, in boat hours, was significantly higher in spring than in fall. Catch rates of trout were higher in fall than in spring, but there were no seasonal differences in catches of salmon. Harvest per boat day did not differ significantly among catch reporting methods, indicating that all three methods could be useful for managers interested in harvest rates. In contrast, total and released catch per boat day differed among reporting methods, with tournament anglers catching more fish in total. Finally, there was little evidence for recall bias in mail-in surveys, indicating that mail-in surveys are useful for collecting unbiased catch data. My study is the most comprehensive angler survey to date for Lake Vänern, and my results should be of immediate use to local fisheries managers and should also be of interest to researchers and managers interested in estimating catch and effort for fisheries at large spatial scales.

Impacts of fishery activities on lake shore environment and options for sustainable management

Over the years, degradation of the lakeshore resources has been going on due to human induced activities. Human activities notably house construction, fish smoking, boat construction and cooking at the landings impact the tree and forest cover along the lakeshore and Islands. The survey was conducted in ten districts surrounding Lake Victoria and the landings sampled were selected with the help of the District Fisheries Officers. Data was obtained from selected fishermen and Key informants at these landing sites. The study examined the extent of knowledge on importance, utilization, threats and conservation of trees/forests at the landings. Results showed that the fishers (98%) were aware of the benefits derived from the trees/forests. According to the respondents, the most commonly used tree species for boat construction were Mvule (40%), Mkibu (20%), Musizi (17%) and Mpewere (11 %). This was mainly because these trees were durable. For house construction, Nsambya (25%), Musizi (24%) and other materials (12%) were the most commonly used. For other activities like fish smoking and cooking at the landing, the Fisherfolk used any type of tree species readily available at the landings. As regards the status of the trees at the landings, most of the respondents (72%) J agreed that due to some fishery related activities some tree species had reduced more than others in the vicinity of most landings. Most respondents said that the, most reduced tree species around the landings were Mvule (36%) and Musizi (22%). Among the fishery related activities that had a significant impact on the trees/forests, construction of houses (44%) and boats (22%) emerged uppermost. Other activities such as fish smoking (14%) and cooking (12%) had the least impact on trees/forests. Generally, there was extensive reduction of trees at the landings. Therefore there was need to regulate cutting of trees and to have specific programmes targeting afforestation at and around fish landings.

Some causes of unreliability of fishery statistics on the African great lakes and possible ways of bettering the statistics

This paper is based on a two year's intensive statistical data collection survey on Lake Kyoga, observations made on Lake Victoria over the last decade occasional visits on Lake Albert (Mobutu) and Lake Malawi. World over, scientists have kept doubting the fisheries statistical figures presented by various African countries. Some countries fail to present any figures. This paper, therefore, narrates most of the causes and possible solutions to those problems.

Reproductive parameters of rhinobatid and urolophid batoids taken as by-catch in the Queensland (Australia) east coast otter-trawl fishery

Reproductive variables are provided for batoids regularly taken as by-catch in the east coast otter-trawl fishery on the inner-mid continental shelf off the south-east and central coasts of Queensland, Australia. Total length at maturity (LT50 and 95% c.i.) for the eastern shovelnose ray Aptychotrema rostrata was 639·5 mm (617·6–663·4 mm) for females and 597·3 mm (551·4–648·6 mm) for males. Litter size (n = 9) ranged from nine to 20 (mean ± s.e. = 15·1 ± 1·2). This species exhibited a positive litter size–maternal size relationship. Disc width at maturity (WD50 and 95% c.i.) for the common stingaree Trygonoptera testacea was 162·7 mm (155·8–168·5 mm) for females and 145·9 mm (140·2–150·2 mm) for males. Gravid T. testacea (n = 6) each carried a single egg in the one functional (left) uterus. Disc width at maturity (WD50 and 95% c.i.) for the Kapala stingaree Urolophus kapalensis was 153·7 mm (145·1–160·4 mm) for females and 155·2 mm (149·1–159·1 mm) for males. Gravid U. kapalensis (n = 16) each carried a single egg or embryo in the one functional (left) uterus. A single female yellowback stingaree Urolophus sufflavus carried an embryo in each uterus. A global review of the litter sizes of shovelnose rays (Rhinobatidae) and stingarees (Urolophidae) is provided.

Towards balanced exploitation and management of the fishery resources of Uganda

A casual study of the hydrological map of Uganda would convince every serious fisherman and fisheater that he is most favoured to be in Uganda. The extent and distribution of the country's aquatic system plus the rich variety of fish species there is promises a fishery potential of considerable magnitude: The open waterways comprised by the Uganda portions of Lakes Victoria, Albert and Edward; and Lakes Kyoga, George plus minor lakes Wamala, Kijanebarora, mutanda, etc. occupy about 15% of the total surface area (91,000 m2; Depart. Land Survey, 1962). Most of the nation's fish supplies are currontly from this source. 1.2. A rich network of permanent and seasonal rivers and streams filling and/or emptying various water systems covers most of Uganda. This aquatic network is associated with a fish fauna whose immense significance as a source of protein is perhaps better appreciated by the local subsistance fisherman and consumer than by the fisheries scientist and manager in this country. Many species of this fish fauna have strong affinities with the open water systems while some are typically riverine. 1.3. Then there are wetlands composed mainly of expanses of swamp, but including some areas of bog. These cover about 2% of the country. While the variety of fish fauna found here is limited by the rather hostile nature of the environment (comparatively de-oxygenated under a canopy of dense stands of emergont vegetation) several specialised fishes e.g. Clarias spp. and Protpterus aethiopicus (Kamongo) occur here. Availability of permanent and seasonal sources of water, well distributed throughout most areas of Uganda, opens up immense potential for a variety of aquaculture practices. However, while active exploitation of much of these fishery resources is currently underway, important questions regarding the magnitudes of the various resource potentials and dynamics, and about suitable levels and modes of exploitation, are yet unanswered. These gaps in knowledge go about the fishery resources of Uganda would hinder formulation of adequate development and management schemes. This short paper examines some of the above problems and suggests some approaches towards balanced oxploitation and management of the fisheries of Uganda.

The effect of hook size on the catch rate and size of the Nile perch Lates niloticus (Linne) fishery in the Napoleon Gulf, Lake Victoria, Uganda

This study was undertaken in Napoleon gulf, Lake Victoria Uganda from July – December 2009. It was conducted in four landing sites; Bukaya (0.41103N, 33.19133E), Bugungu (0.40216N, 33.2028E), Busana (0.39062N, 33.25228E) and Kikondo (0.3995N, 33.21848E) all from Buikwe district (Formerly part of Mukono district). The main aim was to determine the effect of both hook size and bait type on the catch rate (mean weight) and size composition of Nile perch (Lates niloticus) (LINNE) fishery in the Napoleon Gulf, Lake Victoria. The main hook sizes investigated during the experiment were 7, 8, 9, 10, 11 and 12 that were dominantly used in harvesting Nile perch in Napoleon Gulf, Lake Victoria. In this study length, weight and bait type data were collected on site from each boat at that particular fishing spot; since most fishermen in the Napoleon Gulf could sell their fish immediately the catch is caught there and then. The results indicated a total of 873 Nile perch fish samples collected during the study. Statistical tests, descriptive statistics, regression and correlation were all carried out using the Statistical Package for the Social Sciences (SPSS) in addition to Microsoft excel. The bait types in the Gulf ranged from 5-10 cm Total length (TL) haplochromine, 24.5-27 cm TL Mormyrus kannume and 9-24 cm TL Clarias species. The bait types had a significant effect on the catch rate and also on the size composition the fish harvested measured as Total length (ANCOVA F=8.231; P<0.05) despite the fact that bait type had no influence on mean weight of fish captured (ANCOVA F=2.898; P>0.05). Hook sizes used by the fishers had a significant effect on the both the size (TL) composition (ANCOVA F=3.847; P<0.05) and the mean weight (ANCOVA F=4.599; P<0.005) of the Nile perch captured. Investigations indicated hook sizes seven (7) and eight (8) were the ones that harvested the Nile perch above the slot size of 50 cm total length. In general hook sizes indicated to be the main drive in the harvesting of the Nile perch though bait type also contributed toward that. Generally there is need for management to put a law in place on the minimum hook size to be used on the harvesting of the Nile perch and also monitored by the Fisheries Management as a regulatory measure. In addition to that aquaculture should be encouraged to farm the fish for bait at a higher scale in the region in order to avoid depleting the wild stocks already in danger of extinction. Through this kind of venture, both biodiversity conservation and environmental sustainability will be observed in the Lake Victoria basin.

Cast-net fishery on northern portion of Lake Victoria and upper Victoria Nile

This project survey on cost-net was conducted at the Northern portion of Lake Victoria and Upper Victoria Nile. The selected fish -Landing sites, where sampling exercises were carried out include: Loco, Jinja pier (covering Lake Victoria) and Railway bridge, New bridge and Kalange (covering upper Victoria Nile). Research was focused on the cast-net design, target commercial fish stocks, impact of cast-net on the fish stocks, mesh-size and techniques ofcast-netting. The research results show that cast-net fishery destroys fish breeding and nursery grounds and other fish ecosystem. The gear targets Oreochromis niloticus and Occassional by catches e.g. Lates niloticus, Mormyrus Kannume Bagrus docmak and Clarias gariepinus. The multi-panel cast-net of mesh-sizes ranging from i (5lmm) to 6' (152mm) were adaptable by fishermen but they mostly caught immature fish. Nevertheless, this gear showed highest efficiency compared to other gears used at the project area. These research results will be useful to researchers, extension workers and Fishenes, students under taking special research or study on this gear.

Aspects of the fishery and biology of the African catfish Clarias gariepinus (Burchell, 1822) amidst environmental changes in Lake Wamala (Uganda)

Environmental changes are some of the factors that affect fisheries and biological characteristics of fishes. The African catfish Clarias gariepinus (Burchell, 1822) has biological characteristics that enable it to persist under various stressful environmental conditions. However, few studies have examined how the African catfish responds to conditions created by a changing climate. The study examined some of the fishery and biological characteristics of African catfish in Lake Wamala (Uganda) to provide an understanding of their response to changing climatic conditions using data for the period 1950 - 2013. Temperature around the lake increased by 0.02ºC/year since 1980, commensurate with the regional trend, while rainfall was above average since 1996, except in 2004 and 2008. Lake depth was strongly positively correlated with rainfall (r =0.83, n= 6, p<0.05) up to 2000, after which, lake depth decreased amidst increase in rainfall. The contribution of African catfish increased from 20% to 85% and 17% to 78% respectively to commercial and experimental catches respectively between 1975 and 2013 despite the decrease in lake depth. The modal total length, condition factor, food, and fecundity did not change. Only size at first maturity decreased from 37.5 to 30 cm TL in females and 39.5 to 34.2 cm TL in males between 1999/2000 and 2012/2013. The biological characteristics of the African catfish were comparable with those of the same species in other lakes and remained relatively stable. The results suggested that the African catfish has the capacity to persist and/or adjust appropriately under conditions created by climate variability and change, and if properly managed, can sustain the fisheries of Lake Wamala.

‘Ladd traps’ as a visual trap for male and female Queensland fruit fly, Bactrocera tryoni (Diptera: Tephritidae)

Bactrocera tryoni (Froggatt) is Australia's major horticultural insect pest, yet monitoring females remains logistically difficult. We trialled the ‘Ladd trap’ as a potential female surveillance or monitoring tool. This trap design is used to trap and monitor fruit flies in countries other (e.g. USA) than Australia. The Ladd trap consists of a flat yellow panel (a traditional ‘sticky trap’), with a three dimensional red sphere (= a fruit mimic) attached in the middle. We confirmed, in field-cage trials, that the combination of yellow panel and red sphere was more attractive to B. tryoni than the two components in isolation. In a second set of field-cage trials, we showed that it was the red-yellow contrast, rather than the three dimensional effect, which was responsible for the trap's effectiveness, with B. tryoni equally attracted to a Ladd trap as to a two-dimensional yellow panel with a circular red centre. The sex ratio of catches was approximately even in the field-cage trials. In field trials, we tested the traditional red-sphere Ladd trap against traps for which the sphere was painted blue, black or yellow. The colour of sphere did not significantly influence trap efficiency in these trials, despite the fact the yellow-panel/yellow-sphere presented no colour contrast to the flies. In 6 weeks of field trials, over 1500 flies were caught, almost exactly two-thirds of them being females. Overall, flies were more likely to be caught on the yellow panel than the sphere; but, for the commercial Ladd trap, proportionally more females were caught on the red sphere versus the yellow panel than would be predicted based on relative surface area of each component, a result also seen the field-cage trial. We determined that no modification of the trap was more effective than the commercially available Ladd trap and so consider that product suitable for more extensive field testing as a B. tryoni research and monitoring tool.

Assessment of a data-limited, multi-species shark fishery in the Great Barrier Reef Marine Park and south-east Queensland

The status of five species of commercially exploited sharks within the Great Barrier Reef Marine Park (GBRMP) and south-east Queensland was assessed using a data-limited approach. Annual harvest rate, U, estimated empirically from tagging between 2011 and 2013, was compared with an analytically-derived proxy for optimal equilibrium harvest rate, UMSY Lim. Median estimates of U for three principal retained species, Australian blacktip shark, Carcharhinus tilstoni, spot-tail shark, Carcharhinus sorrah, and spinner shark, Carcharhinus brevipinna, were 0.10, 0.06 and 0.07 year-1, respectively. Median U for two retained, non-target species, pigeye shark, Carcharhinus amboinensis and Australian sharpnose shark, Rhizoprionodon taylori, were 0.27 and 0.01 year-1, respectively. For all species except the Australian blacktip the median ratio of U/UMSY Lim was <1. The high vulnerability of this species to fishing combined with life history characteristics meant UMSY Lim was low (0.04-0.07 year-1) and that U/UMSY Lim was likely to be > 1. Harvest of the Australian blacktip shark above UMSY could place this species at a greater risk of localised depletion in parts of the GBRMP. Results of the study indicated that much higher catches, and presumably higher U, during the early 2000s were likely unsustainable. The unexpectedly high level of U on the pigeye shark indicated that output-based management controls may not have been effective in reducing harvest levels on all species, particularly those caught incidentally by other fishing sectors including the recreational sector. © 2016 Elsevier B.V.

Effects of fishery protection on biometry and genetic structure of two target sea cucumber species from the Mediterranean Sea

Sea cucumber fisheries are now occurring in most of the tropical areas of the world, having expanded from its origin in the central Indo-Pacific. Due to the overexploitation of these resources and the increasing demand from Asian countries, new target species from Mediterranean Sea and northeastern Atlantic Ocean are being caught. The fishery effects on biometry and genetic structure of two target species (Holothuria polii and H. tubulosa) from Turkey, were assessed. The heaviest and largest individuals of H. polii were found into the non-fishery area of Kusadasi, also showing the highest genetic diversity. Similar pattern was detected in H. tubulosa, but only the weight was significantly higher in the protected area. However, the observed differences on the fishery effects between species, could be explained considering the different percentage of catches (80% for H. polii and 20% for H. tubulosa).

Genetic differentiation among Parastichopus regalis populations in the Western Mediterranean Sea: potential effects from its fishery and current connectivity

Parastichopus regalis (Cuvier, 1817) is the most expensive seafood product on the Catalonian market (NE Spain), with prices at approximately 130 €/Kg (fresh weight). Despite its ecological and economic importance, biological and genetic information on this sea cucumber species is scarce. Here, we provide both the first insight on the genetic structure of P. regalis using sequences of cytochrome oxidase I (COI) and 16S genes and a morphological description of its population. Individual sea cucumbers were collected in six locations along the Spanish Mediterranean coast, including an area under fishery pressure (Catalonia). We found high haplotype diversity and low nucleotide diversity for both genes, with higher levels of genetic diversity observed in the COI gene. The population pairwise fixation index (FST), AMOVA and correspondence analysis (CA) based on the COI gene revealed significant genetic differentiation among some locations. However, further analysis using nuclear markers (e.g., microsatellites) is necessary to corroborate these results. Moreover, the genetic and morphological data may indicate fishery effects on the Catalonian population with a decrease in the size and weight averages and lower genetic diversity compared with locations that lack fishery pressure. For the appropriate management of this species, we suggest the following: 1) accurately assessing the stock status along the Spanish coasts; 2) studying the reproductive cycle of this target species and the establishment of a closed fishery season according to the reproductive cycle; and 3) establishing protected areas (i.e., not take zones) to conserve healthy populations and favour recruitment in the nearby areas.

Life Cycle of Deccan Trap Magma Chambers: A Crystal Scale Elemental and Strontium Isotopic Investigation

The Deccan Trap basalts are the remnants of a massive series of lava flows that erupted at the K/T boundary and covered 1-2 million km2 of west-central India. This eruptive event is of global interest because of its possible link to the major mass extinction event, and there is much debate about the duration of this massive volcanic event. In contrast to isotopic or paleomagnetic dating methods, I explore an alternative approach to determine the lifecycle of the magma chambers that supplied the lavas, and extend the concept to obtain a tighter constraint on Deccan’s duration. My method relies on extracting time information from elemental and isotopic diffusion across zone boundary in an individual crystal. I determined elemental and Sr-isotopic variations across abnormally large (2-5 cm) plagioclase crystals from the Thalghat and Kashele “Giant Plagioclase Basalts” from the lowermost Jawhar and Igatpuri Formations respectively in the thickest Western Ghats section near Mumbai. I also obtained bulk rock major, trace and rare earth element chemistry of each lava flow from the two formations. Thalghat flows contain only 12% zoned crystals, with 87Sr/86Sr ratios of 0.7096 in the core and 0.7106 in the rim, separated by a sharp boundary. In contrast, all Kashele crystals have a wider range of 87Sr/86Sr values, with multiple zones. Geochemical modeling of the data suggests that the two types of crystals grew in distinct magmatic environments. Modeling intracrystalline diffusive equilibration between the core and rim of Thalghat crystals led me to obtain a crystal growth rate of 2.03x10-10 cm/s and a residence time of 780 years for the crystals in the magma chamber(s). Employing some assumptions based on field and geochronologic evidence, I extrapolated this residence time to the entire Western Ghats and obtained an estimate of 25,000 – 35,000 years for the duration of Western Ghats volcanism. This gave an eruptive rate of 30 – 40 km3/yr, which is much higher than any presently erupting volcano. This result will remain speculative until a similarly detailed analytical-modeling study is performed for the rest of the Western Ghats formations.