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A major reason why conservation aquaculture is needed to improve the success of aquaculture-assisted fisheries is that traditional production aquaculture produces fish with mal-adaptive behaviors. These behaviors can be produced via domestication and culture techniques, and preventing these mal-adaptive behaviors requires integrating improvements in genetic management and culture protocols. The genetic protocols needed to minimize hatchery-induced genetic changes have received considerable attention, but changing the way fish are raised has received less effort. Conservation aquaculture cultures fish in environments that resemble their native habitats so that when stocked, they behave like wild fish rather than hatchery fish. A purpose built-conservation aquaculture facility can also be used to learn about a species’ behavior and how it reacts to changes in the environment, something which can be difficult or expensive to study in the wild. These observations can then be used to help direct both propagation and recovery management. This paper provides the rationale for why genetic management, culture systems, and management practices need to be altered to produce fish that are behaviorally similar to wild fish for aquaculture-assisted fisheries programs. It then provides a description of some of the behaviors of the endangered Rio Grande silvery minnow Hybognathus amarus that were observed at the Los Lunas Silvery Minnow Refugium, a purpose-built conservation aquaculture facility, and explains how some of these behaviors can be used in culture and recovery management. Behaviors described are: schooling; predator avoidance; feeding behavior; use of vegetation for cover and predator avoidance; habitat use by bottom substrate; location in the water column; upstream movement via a fish ladder; movement upstream in a high-velocity channel; response to changes in water level; spawning behavior; seine avoidance; and Kaah-chee-nyee Srkaash, a behavior described for the first time.

Federally endangered Rio Grande Silvery Minnows (RGSM; Hybognathus amarus) were raised in one of three culture regimes: intensively, with only a hatchery diet; semi-intensively with access to natural food and hatchery diet supplementation; and with only natural food available at the Los Lunas Silvery Minnow Refugium (Los Lunas, New Mexico), a naturalized conservation refugium designed to mimic the natural environment of the RGSM in the Rio Grande. The project compared each culture regime and assessed differences and similarities in lipid and fatty acid content between feeding an artificial diet and consumption of natural food items in this species. After 117 d, whole-body lipid levels and fatty acid profiles were measured in each group and compared with values for wild RGSM. Fish fed the hatchery diet exclusively or as supplementary feed had significantly higher percent lipid (15.5% ± 0.5% and 10.6% ± 0.1%, respectively) than fish raised without access to the diet. Both groups had significantly higher percent lipid than fish raised in the refugium or wild fish (8.3% ± 0.1% and 7.8% ± 0.2%, respectively). Condition factor differed among groups and was highest in fish fed the hatchery diet (1.00) followed by fish supplemented with the hatchery diet (0.93), refugium fish (0.91), and wild fish (0.90). In this respect, refugium fish appeared more similar to wild fish than fish fed the hatchery diet or offered the diet as a supplement. Comparison of fatty acid profiles among groups showed marked differences among wild fish, refugium fish, and those fed the hatchery diet, either exclusively or as supplementary feed. Total omega-3 fatty acids, expressed as percentage of total fatty acids, were highest in wild fish but similar among other groups. Total omega-6 fatty acids showed an opposite trend, with five to nine times higher percentages of linoleic acid observed among fish from the three culture regimes compared with wild fish. Significant differences in lipid content and fatty acid composition between wild RGSM and cultured silvery minnows reflected their respective diets and culture regimes. Given similarities in fat content and condition factor with wild RGSM, we conclude that fish in the refugium do not require supplemental feeding with an artificial diet for this type of naturalized conservation management. Results from this study show that RGSM readily forage on natural food items present and also artificial feed when available, indicating dietary plasticity, which is advantageous for fish culture and future recovery.

The lower lethal temperature of the endangered Rio Grande silvery minnow, Hybognathus amarus, was estimated from survival rates of fish overwintered in above-ground tanks. Temperature went to 0.0°C both winters. In 2012–2013, survival of Age class 0 fish was 79.87%, and in 2013–2014, survival of Age class 1 fish was 97.1%, suggesting that if Rio Grande silvery minnow is subjected to seasonal temperature changes, lower lethal temperature is ≤0.0°C. Results show that heating hatchery water in the winter is unnecessary. Additionally, current management guidelines that preclude reintroduction of the species into river sections where winter temperatures are ≤1°C must be reevaluated.

Head length, head depth, head width, body depth, body width, caudal depth, and caudal width and total length and BW were measured for 71 backcross full sibs between the interspecific backcross F1 (female channel catfish [Ictalurus punctatus] × male blue catfish [Ictalurus furcatus]) female × blue catfish male. Body measurements were corrected for both size and the relationship between relative body shape and size, which is critical but usually ignored in fish research. Amplified fragment length polymorphism analysis was used for construction of a QTL map with 44 linkage groups. Eleven of 44 linkage groups had at least 1 significant QTL (P ≤ 0.05) and 11 of 44 at P = 0.10. Linkage group 19 was unique as it had multiple QTL for every trait measured, except for caudal width for which no QTL was identified on any linkage group. Approximately half of the markers measured were associated with positive effects (increase in size) on the traits and half had negative effects (decrease in size). Linkage groups 5, 9, 18, 20, 39, and 40 were significant for multiple traits and always had a trait negative effect. Total length is represented on the map by the most linkage groups and the most markers. The linkage relationships found among BW, total length, and the 7 morphometric traits indicated that multiple trait marker-assisted selection to simultaneously increase BW body depth, body width, and caudal depth while decreasing the head traits with the goal to increase body weight and carcass yield would be very difficult. Multiple genetic enhancement approaches would likely be needed to simultaneously improve BW and body conformation.

The objective of the this research was to determine the heritabilities and response to selection for fecundity, percent kg per kilogram body weight for channel catfish females induced to ovulate with luteinizing hormone releasing hormone analogue (LHRHa) for the production of hybrid catfish embryos. Age and/or environmental effects influences the reproductive traits measured over two spawning seasons. When the fish were three years old the relative fecundity was 10,247 and 10,127 for the select and control lines, respectively. The percent kg per kilogram female for select line was 34.7 and 3,311 and for the control was 35.5 and 3,124, respectively. Realized heritabilities were 0.10, − 0.03, and 0.06 for fecundity, percent hatch and fry per kilogram female, respectively. When the fish were four years old, the relative fecundity was 9429 and 8968 for the select and control lines, respectively. The percent hatch and fry per kilogram female for the select progeny was 9.8 and 835 and the control progeny was 13.3 and 1026, respectively. Realized heritabilities were 0.42, − 0.13, and − 0.06 for fecundity, percent hatch and fry per kilogram female, respectively. A response to selection for fecundity was observed for both years with realized heritability ranging from 0.10 to 0.42. This trait appears to have additive genetic variation and can be improved via selection. Heritabilities for percent hatch and fry/kg were near zero, and likely cannot be improved via mass selection.

The endangered Rio Grande silvery minnow Hybognathus amarus was cultured in 2.44-m-diameter outdoor tanks in a 131-day yield trial to assess growth, survival, and percentage of taggable-sized fish ( >35 mm total length) when stocked at 500/tank (1.07 million/ha), 1,000/tank (2.14 million/ha), and 1,500/tank (3.21 million/ha). At harvest, fish averaged 45.6 mm and 0.94 g in the 500/tank treatment, 42.6 mm and 0.74 g in the 1,000/tank treatment, and 38.4 mm and 0.55 g in the 1,500/tank treatment; the differences were significant ( P = 0.05). Survival in the three treatments was 70%, 64%, and 52%, respectively, but the differences were not significant. Percent taggable-sized fish was 86%, 89%, and 65%, respectively, but the differences were not significant. Yield was 672.5 kg/ha, 1,026.6 kg/ha, and 887.8 kg/ha, respectively; yield in the 1,000/tank treatment was significantly greater than that in the 500/tank treatment, but was not significantly greater than that of the 1,500/tank treatment. This facility is a conservation facility and a major goal is to raise fish without formulated feed. Fertilization produced good growth for the first month, but little growth occurred during the second month so supplemental feed had to be used for the final 60 d of the yield trial.

Adoption of the hybrid catfish (channel catfish, Ictalurus punctatus , female × blue catfish I. furcatus , male) is increasing in the catfish industry. The most effective way to produce fry is hormone induced spawning of females coupled with hand stripping and in vitro fertilization. The success of common carp pituitary extract (CPE), luteinizing hormone releasing hormone analog (LHRHa) injections and LHRHa implants for producing hybrid catfish fry was investigated over the past 15 years. Data from 65 studies, 25, 20 and 20 for CPE, LHRHa injections, and LHRHa implants, respectively, were evaluated. Mean fry/kg female body weight (all females) produced was 948, 2483 and 2765 for CPE, LHRHa injections, and LHRHa implants, respectively. LHRHa administered as an injection or implant produced more (P

This article describes the initial season‐long yield trial of raising the endangered Rio Grande silvery minnow, Hybognathus amarus, in the conservation rearing facility at the Los Lunas Silvery Minnow Refugium. Ten thousand fish (90,900/ha) were stocked on June 22, 2010. Production was based on a total of 653 mL (5.936 L/ha) of 11‐37‐0 N‐P‐K and 5.5 kg (50 kg/ha) of alfalfa pellets. Fish were harvested in October; almost all were harvested 18–27 October. At stocking, fish averaged 21.7 mm total length and mean weight was 0.10 g. At harvest, fish averaged 48.98 mm and 1.12 g. Fish were sampled monthly, and increased lengths and weights through the study were significant (P = 0.05). Five thousand eight hundred ninety‐two fish were harvested (58.92% survival). Yield was 59.99 kg/ha. Temperature, dissolved oxygen (DO), pH, un‐ionized ammonia, nitrite, turbidity, alkalinity, and chloride were measured at seven sites throughout the outdoor refugium. Secchi disc visibility was measured in the stream and in the ponds. Only two variables (DO and pH) went outside permitted values, but were easily corrected. Harvest was difficult due to the many different naturalized areas consisting of varying depths, channel widths, and substrates.

The Los Lunas Silvery Minnow Refugium is a conservation fish hatchery that produces the endangered Rio Grande silvery minnow ( Hybognathus amarus Girard [Cyprinidae]). The major management goal of a conservation fish hatchery is to raise fish in a naturalized environment that is similar to their native ecosystem, including native vegetation. This is diametrically opposed to management at traditional fish hatcheries, where rooted plants in fish culture units are considered to be weeds because they can cause management problems; most notably, these plants interfere with fish harvest. Fifteen native wetland and 8 native upland species of plants were installed in the naturalized outdoor conservation fish-rearing facility. The plants were used to produce shade, shelter from predators, places for food to colonize, areas of low-velocity water, and to create riparian overbank areas that could be inundated in order to simulate floodplains along the Rio Grande. The plants have thrived at the facility. Continuous manual weeding is required from March to October to remove weeds and to keep sedges and rushes from filling the ponds. Observations indicate that the plants are achieving the intended purposes.

The interspecific hybridization of channel catfish, Ictalurus punctatus, females with blue catfish, I. furcatus, males has been identified as a method to further improve production; however, lack of spawning success has affected its commercial application. To facilitate our understanding of the interaction of brood stock nutrition and reproductive performance, we evaluated the interaction of feed quality and feeding frequency. Channel catfish females were classified into two genetic groups, namely, high and low spawning. The treatments were offered during the spring season 70–90 d prior to the start of the spawning season. Induced reproduction was performed using luteinizing hormone releasing hormone analog. Condition of the fish as well as reproductive performance using spawning success, egg production, egg size, and fertilization at 48 h were determined. Changing protein level of the diet from 32 to 42% did not influence spawning, fecundity, or fertilization, but affected egg size and biochemical composition of the eggs. Increasing the feeding frequency from three to six times per week negatively affected spawning in one of the two genetics groups, did not affect egg production and egg fertilization, but had a significant effect on egg size. Older fish performed better than younger fish in terms of spawning success and egg production.

This article describes an airlift pump used to produce a circular flow in a fish culture tank that does not attach to the tank. The design produces an airlift pump that does not swing back and forth or float upwards while in use. It is easy to build, inexpensive, and can be quickly installed and removed so that it does not interfere with sampling or harvest. The airlift pump was evaluated during a 30-d survival trial with the endangered Rio Grande silvery minnow (Hybognathus amarus) in 2.44-m-diameter circular tanks (3,666 l). Because the fish is endangered, all new culture units must be evaluated in a survival trial. To be able to use a new 15-tank system, survival had to be evaluated in a random representation of three tanks. U.S. Fish and Wildlife Service, which regulates all activities with this endangered species, decided that permitted take (maximum permitted mortality) was 60% for the survival trial; consequently, survival >40% in each tank would be considered successful. Two airlift pumps were placed in each tank. The two airlift pumps moved a mean±SD of 33.697±5.563 l/min; this produced total tank turnovers through the airlift pumps of 110.65±16.93 min. Water velocities were measured at nine locations in the tanks. Water velocities were 0.0-0.04 m/sec. Dissolved oxygen concentration never went below 6.30 mg/l. The airlift pumps operated flawlessly and required no maintenance. They produced water velocities preferred by the fish and helped keep dissolved oxygen concentration above the permitted minimum (5 mg/l). The airlift pumps will be used in future fish culture activities in these and other tanks. Survival in the three tanks was 78%, 94% and 96%; overall survival was 89.3%. Because take (10.7%) was under the permitted level (60%), the trial was successful., Ovaj rad opisuje zračnu pumpu koja se koristi za stvaranje kružnoga toka u spremniku za uzgoj ribe koja se ne pričvršćuje za spremnik. Takav dizajn pomaže pumpi da se ne miće naprijed-nazad ili da pluta prema gore dok se koristi. Lako ju je izraditi, nije skupa te ju je jednostavno montirati i ukloniti da ne smeta prilikom uzorkovanja ili ulova. Zračna pumpa je ispitivana tijekom 30-dnevnog testa preživljavanja ugrožene vrste srebrne bjelice iz rijeke Rio Grande (Hybognathus amarus) u kružnim tankovima dijametra širine 2,44 metra (3.666 l). Budući da je ova vrsta ugrožena, potrebno je procijeniti sve nove jedinice za uzgoj pomoću testa preživljavanja. Kako bi bilo moguće koristiti novi sustav od 15 spremnika, potrebno je procijeniti preživljavanje u nasumičnom prikazu triju spremnika. Fish and Wildlife Service iz S.A.D.-a, koji regulira sve aktivnosti ove ugrožene vrste, odlučio je da je maksimalna dozvoljena smrtnost 60% za test preživljavanja; prema tome, preživljavanje >40% u svakom spremniku se smatra uspješnim. Po dvije zračne pumpe su stavljene u svaki spremnik. Dvije zračne pumpe su pomicale prosječno±SD od 33,697±5,563 l/min; ovo je proizvelo kompletnu izmjenu volumena spremnika pomoću zračnih pumpi od 110,65±16,93 min. Brzina vode se mjerila na devet mjesta u spremnicima. Brzina vode je bila 0,0-0,04 m/s. Koncentracija otopljenog kisika ni u jednom trenutku nije pala ispod 6,30 mg/l. Zračne pumpe su radile besprijekorno i nisu zahtijevale održavanje. Proizvodile su brzinu vode koja je pogodovala ribi te je omogućavala da se koncentracija otopljenog kisika održi iznad dozvoljenog minimuma (5 mg/l). Zračne pumpe će se koristiti u budućim aktivnostima uzgoja ribe u ovim i drugim spremnicima. Preživljavanje u trima spremnicima bilo je 78%, 94% i 96%; ukupno preživljavanje bilo je 89,3%. Budući da je smrtnost bila (10,7%) ispod dozvoljene razine (60%), test se smatra uspjelim.