James S. Diana

Aquaculture production and biodiversity conservation.

This overview examines the status and trends of seafood production, and the positive and negative impacts of aquaculture on biodiversity conservation. Capture fisheries have been stabilized at about 90 million metric tons since the late 1980s, whereas aquaculture increased from 12 million metric tons in 1985 to 45 million metric tons by 2004. Aquaculture includes species at any trophic level that are grown for domestic consumption or export. Aquaculture has some positive impacts on biodiversity; for example, cultured seafood can reduce pressure on overexploited wild stocks, stocked organisms may enhance depleted stocks, aquaculture often boosts natural production and species diversity, and employment in aquaculture may replace more destructive resource uses. On the negative side, species that escape from aquaculture can become invasive in areas where they are nonnative, effluents from aquaculture can cause eutrophication, ecologically sensitive land may be converted for aquaculture use, aquaculture species may consume increasingly scarce fish meal, and aquaculture species may transmit diseases to wild fish. Most likely, aquaculture will continue to grow at significant rates through 2025, and will remain the most rapidly increasing food production system.

Range, activity, and habitat of large, free-ranging brown trout in a Michigan Stream

Abstract Little is known about behavior patterns and habitat use of large (400+ mm total length) brown trout Salmo trutta. We used radio telemetry to monitor the movements of eight large (437–635 mm), free-ranging brown trout for up to 346 d. Total range of movement upstream and downstream varied from 370 m to 33,420 m. At some time during the year, six of the fish moved out of an area protected with no-kill fishing regulations, even though none of them were tagged and released closer than 2 km from its boundaries. However, four of five fish tracked during the height of the fishing season spent 87% of their time in the protected area. The fish appeared to have separate winter and summer ranges. Five of six fish tracked during autumn–winter moved upstream about 10 km to slower, deeper parts of the river between August and November, and remained there at least through the following April. The part of the river used as autumn–winter range was considered only marginal habitat for brown trout during summer due...

Seasonal Energy Dynamics of the Alewife in Southeastern Lake Michigan

Abstract Alewives Alosa pseudoharengus collected in southeastern Lake Michigan from October 1979 to October 1981 were analyzed for caloric content, lipid, and lean dry (lipid-free) weight. The relative seasonal change in energy density (kcal/g wet weight) was similar in adults and immature fish, although immatures generally had lower caloric equivalents. Seasonal lows in caloric equivalents occurred in April for immature fish in their first year (1.03 kcal/g) and in June for adults (1.30 kcal/g), whereas maxima were found in October for all age groups (2.30 kcal/g). Somatic energy losses during winter were 27% for adult females and 23% for males; spawning-related losses were higher (37% and 45%, respectively). Percent lipid followed the same seasonal trends as caloric equivalents with maxima in the fall (17% wet weight) and minima in late spring-summer (3–5%). Approximately 80% of gonad growth and maturation took place from April to late May when feeding was at a minimum. Energy requirements for gonad gro...

Relationships among nutrient inputs, water nutrient concentrations, primary production, and yield of Oreochromis niloticus in ponds

Abstract Experiments were run to assess the physical, chemical, and biological processes leading to increased production of fertilized fish ponds in Thailand for approximately 5 months during wet season 1984 and wet and dry seasons 1985. Eight or 12 ponds (250 m 2 ) were stocked with male Nile tilapia at 1 fish/m 3 . Ponds received fertilizer according to three different schemes: (1) low input inorganic (0.27 kg triple superphosphate, equalling 0.12 kg P ha −1 d −1 ); (2) high input organic (71.4 dry kg chicken manure ha −1 d −1 ); and (3) high input inorganic (14.3 kg triple superphosphate ha −1 d −1 and 4.3 kg urea ha −1 d −1 ). Treatments 2 and 3 yielded identical loadings of 2 kg N ha −1 d −1 and 3.2 kg P ha −1 d −1 . Ponds receiving high fertilizer inputs had higher nutrient concentrations in water, higher primary production, and higher fish production than ponds treated with low fertilizer inputs. At high fertilizer inputs, chlorophyll a content and primary production were similar for all ponds, but fish growth and adult yield were significantly greater in organically rather than inorganically fertilized ponds. This was attributed to increased heterotrophy by fish in ponds treated with organic fertilizer. Regression analysis indicated only marginally predictive relationships between total inorganic nitrogen or total phosphorus concentration in the water and primary production. Secchi disk depth was a reasonable predictor of both primary production and chlorophyll a ( r 2 =0.67). Diel temperature stratification was low, but correlated with air temperature, solar radiation, rainfall, and wind velocity. Diel oxygen stratification was more pronounced with inorganic fertilization, probably due to greater water clarity and more even distribution of primary production in organically fertilized ponds. Yield of stocked fish was correlated with rainfall and primary production.

Influence of Nile tilapia (Oreochromis niloticus) stocking density in cages on their growth and yield in cages and in ponds containing the cages

Abstract An experiment was conducted for 90 days at the Asian Institute of Technology in Thailand to investigate the appropriate stocking density of large Nile tilapia placed in cages in earthen ponds where small Nile tilapia were stocked in open water to utilize the wastes derived from the cages. Large male tilapia (141 ± 11.1–152 ± 2.1 g) were stocked at 30, 40, 50, 60, and 70 fish m−3 in 4-m3 net cages. One cage was suspended in each of 15 earthen ponds, and three replicates were used for each density. Small male tilapia (54 ± 2.3–57 ± 1.2 g) were stocked at 2 fish m−3 in open water of all ponds. Caged tilapia were fed twice daily at 3%, 2.5%, and 2% body weight day−1 during the first, second, and third month, respectively, with commercial floating pellets containing 30% crude protein. Water quality was analyzed biweekly. Stocking densities of caged tilapia had significant (P

Growth, Maturation, and Production of Northern Pike in Three Michigan Lakes

Abstract Differences in the age at first maturation, as well as timing and magnitude of growth (body and gonad) were examined for northern pike Esox lucius from three lakes in Michigan. The lakes varied in latitude (42 to 46°N), ice-free season (210 to 248 days), and total mortality (Z = 0.28 to 0.85). Body and gonad calorific equivalents were similar among all three lake populations. Male and female northern pike from all lakes and age classes 1–3 had significant accumulation of somatic energy during summer and winter and depletion of reserves over spawning. Testicular growth occurred entirely in the summer, whereas ovarian growth occurred mainly over winter. Females invested 6- to 18-fold more energy into gonads than did males. Total winter growth was significant in both sexes and all lakes. Individual body and gonad growth over the first 3 years of life for northern pike varied little among lakes. Age at first maturation varied significantly among lakes; the earliest maturation occurred in the lake of ...

Responsible Aquaculture in 2050: Valuing Local Conditions and Human Innovations Will Be Key to Success

As aquaculture production expands, we must avoid mistakes made during increasing intensification of agriculture. Understanding environmental impacts and measures to mitigate them is important for designing responsible aquaculture production systems. There are four realistic goals that can make future aquaculture operations more sustainable and productive: (1) improvement of management practices to create more efficient and diverse systems at every production level; (2) emphasis on local decisionmaking, human capacity development, and collective action to generate productive aquaculture systems that fit into societal constraints and demands; (3) development of risk management efforts for all systems that reduce disease problems, eliminate antibiotic and drug abuse, and prevent exotic organism introduction into local waters; and (4) creation of systems to better identify more sustainably grown aquaculture products in the market and promote them to individual consumers. By 2050, seafood will be predominantly sourced through aquaculture, including not only finfish and invertebrates but also seaweeds.

Life cycle assessment of Chinese shrimp farming systems targeted for export and domestic sales

We conducted surveys of six hatcheries and 18 farms for data inputs to complete a cradle-to-farm-gate life cycle assessment (LCA) to evaluate the environmental performance for intensive (for export markets in Chicago) and semi-intensive (for domestic markets in Shanghai) shrimp farming systems in Hainan Province, China. The relative contribution to overall environmental performance of processing and distribution to final markets were also evaluated from a cradle-to-destination-port perspective. Environmental impact categories included global warming, acidification, eutrophication, cumulative energy use, and biotic resource use. Our results indicated that intensive farming had significantly higher environmental impacts per unit production than semi-intensive farming in all impact categories. The grow-out stage contributed between 96.4% and 99.6% of the cradle-to-farm-gate impacts. These impacts were mainly caused by feed production, electricity use, and farm-level effluents. By averaging over intensive (15%) and semi-intensive (85%) farming systems, 1 metric ton (t) live-weight of shrimp production in China required 38.3 ± 4.3 GJ of energy, as well as 40.4 ± 1.7 t of net primary productivity, and generated 23.1 ± 2.6 kg of SO(2) equiv, 36.9 ± 4.3 kg of PO(4) equiv, and 3.1 ± 0.4 t of CO(2) equiv. Processing made a higher contribution to cradle-to-destination-port impacts than distribution of processed shrimp from farm gate to final markets in both supply chains. In 2008, the estimated total electricity consumption, energy consumption, and greenhouse gas emissions from Chinese white-leg shrimp production would be 1.1 billion kW·h, 49 million GJ, and 4 million metric tons, respectively. Improvements suggested for Chinese shrimp aquaculture include changes in feed composition, farm management, electricity-generating sources, and effluent treatment before discharge. Our results can be used to optimize market-oriented shrimp supply chains and promote more sustainable shrimp production and consumption.

Food Habits of Angler-Caught Salmonines in Western Lake Huron

Stomachs were collected from 1,833 trout and salmon caught in western Lake Huron by tournament and volunteer anglers during 1983–1986. Diets of all species collected were dominated by rainbow smelt (Osmerus mordax; 67% by number) and alewives (Alosa pseudoharengus; 29%). Although predator and prey lengths had significant positive regressions, the strength of the relationships (r2 < 0.05) indicated little selection of prey by length. Number of prey per stomach ranged from 0 to 79, but most predators contained less than 5 prey. Alewife abundance in the diet decreased significantly over summer, with a concomitant increase in rainbow smelt consumption. The ratio of alewives to rainbow smelt also varied with year. Diet of salmonines from western Lake Huron was quite different from that in other Great Lakes, particularly in the preponderance of rainbow smelt and in low overall diversity. I suggest that stocking rates and other regulations should consider lake differences in management of trout and salmon populations.

Simulation of Mechanisms Causing Stunting in Northern Pike Populations

Abstract Some mechanisms hypothesized to cause stunting of northern pike Esox lucius include overpopulation and competition, lack of appropriately sized prey, and lack of thermal refuges in midsummer. The objective of this work was to use an energetics model of northern pike growth over 3 years to test the effects of these mechanisms on stunting. Simulations for females indicated the following: (1) competition-based stunting could occur when food resources were reduced by only 5–10% per individual, such that size at age 3 would be reduced by up to 51%; (2) lack of appropriately sized prey could result in stunting (up to 35% of a northern pikes annual ration often comes from large and rare prey), such that size at age 3 could be reduced 80%; (3) inappropriate thermal regimes could reduce northern pike growth up to 58%, but only under extremely warm conditions.