Indigenous protected areas in Sea Country: Indigenous‐driven collaborative marine protected areas in Australia

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The “Nemo Effect”: Perception and reality of Finding Nemo's impact on marine aquarium fisheries

Global audiences are increasingly being exposed to digital media with fictitious storylines that draw on animal characters involuntarily entering wildlife trades . An understudied problem in wildlife trade is the potential for motion pictures to influence their audience's desire to become more acquainted, often via acquisition, with animals portrayed in the films. The 2003 Disney motion picture Finding Nemo connected audiences with a wildlife trade already commonplace: the marine aquarium trade. In this trade, fisheries supply live coral reef organisms to millions of public and private aquaria worldwide. Here, we examine the perception and reality of Finding Nemo's impact (coined the “Nemo Effect”) on the fisheries of the species complex representing the film's primary protagonist “Nemo” (Amphiprion ocellaris/percula). Import and export figures show little evidence for fan‐based purchases of wild‐caught fish immediately (within 1.5 years of release) following the film. We argue that the perceived impact on these species, driven by popular media with an emotive but scientifically uninformed approach to conserving coral reef ecosystems, can be more damaging to the cause of conservation than helpful. This perspective is intended to encourage marine aquarium trade stakeholders to consider the ecological and social repercussions of both media driven consumption and opposition to the trade. Using lessons learned from Finding Nemo, we discuss the likely impacts the sequel, Finding Dory, will have on wild populations of its protagonist “Dory” (Paracanthurus hepatus).     

Fillet Quality and Processing Attributes of Postsmolt Atlantic Salmon,Salmo salar,Fed a Fishmeal‐free Diet and a Fishmeal‐based Diet in Recirculation Aquaculture Systems

Many studies have evaluated the adequacy of alternate ingredient diets for Atlantic salmon, Salmo salar, mainly with focus on fish performance and health; however, comprehensive analysis of fillet quality is lacking, particularly for salmon fed these diets in recirculation aquaculture systems (RAS). To this end, a study was conducted comparing fillet quality and processing attributes of postsmolt Atlantic salmon fed a fishmeal‐free diet (FMF) versus a standard fishmeal‐based diet, in replicate RAS. Mean weight of Atlantic salmon fed both diets was 1.72 kg following the 6‐mo trial and survival was >99%. Diet did not affect (P > 0.05) processing and fillet yields, whole‐body proximate composition(fat, moisture, protein), fillet proximate composition, cook yield, fillet texture, color, or omega‐3 fatty acid fillet content, including eicosapentaenoic acid and docosahexaenoic acid levels. Whole‐body ash content was greater in salmon fed the FMF diet. The FMF diet resulted in a wild fish‐in to farmed fish‐out ratio of 0:1 per Monterey Bay Aquarium's Seafood Watch criteria due to its fishmeal‐free status and use of lipids from fishery byproduct. Overall, fillet quality and processing attributes were generally unaffected when feeding a diet devoid of fishmeal to postsmolt Atlantic salmon cultured in RAS. [Correction added on 7 September 2017, after first online publication: the P value in Abstract has been changed from “P < 0.05” to “P > 0.05”.].     

Reproductive cycle of the Amazonian planktivorous catfish Hypophthalmus marginatus (Siluriformes,Pimelodidae)

We evaluated the annual process of oocyte and ovarian development of the planktivorous Amazonian catfish, the mapará (Hypophthalmus marginatus), aiming to support captive reproduction for domestication. A total of 149 females were captured from the Tocantins River at the Tucuruí Dam (3°49'55"S, 49°39'9"W) in 13 sampling events. For each individual, we evaluated ovary histology and plasma steroid concentrations. Two annual reproductive cycles, with similar characteristics, including a long period of rest, a short vitellogenic stage and a well‐defined spawning season from November to March, were described. A 17β‐estradiol (E₂) rise and a 17α,20β‐dihydroxy‐4‐pregnen‐3‐one (DHP) peak were associated with vitellogenesis and spawning season, respectively, in the first cycle but not in the second reproductive cycle. In conclusion, the studied species presents a reproductive cycle similar to that of other migratory total spawners; however, unusually for this group of fish, there were three (but not two) batches of vitellogenic oocytes in “in maturation” and “mature” stage ovaries, pointing to the possibility of more than one spawn during the spawning season.     

A comparative molecular study of the presence of “Candidatus arthromitus” in the digestive system of rainbow trout,Oncorhynchus mykiss (Walbaum), healthy and affected with rainbow trout gastroenteritis

Observations were made using histopathological techniques in conjunction with a nested polymerase chain reaction (PCR) protocol for the specific detection of “Candidatus arthromitus” on DNA extracted from wax‐embedded tissues and fresh digestive contents of rainbow trout. Samples positive for “Candidatus arthromitus” DNA included fish with rainbow trout gastroenteritis (RTGE), clinically normal cohabiting fish, and apparently healthy controls from RTGE positive and RTGE negative sites. The results obtained from the PCR were confirmed by nucleotide sequencing. “Candidatus arthromitus” DNA was found in distal intestine as well as in sections of pyloric caeca, suggesting that both these locations are appropriate for molecular detection of “Candidatus arthromitus” DNA in trout. Furthermore, rainbow trout fry distal intestinal samples from two different hatcheries where RTGE had not been reported were also positive. Differences in “Candidatus arthromitus” DNA detection between paraffin wax‐embedded and fresh digestive content samples from the same fish suggested that it may be predominantly epithelium‐associated in healthy trout. Parallel histopathological observations indicated that pyloric caeca are the preferred site for visualizing segmented filamentous bacteria (SFB) in trout with RTGE. The results of this study showed that the presence of SFB was not invariably associated with clinical disease and that more information is required to understand the role of these organisms.     

Scanning Electron Microscopy of “Saddleback” Lesions Associated with Experimental Infections of Flavobacterium columnare in Channel Catfish,Ictalurus punctatus (Siluriformes: Ictaluridae), and Zebrafish,Danio rerio (Cypriniformes: Cyprinidae)

Laboratory‐reared, specific pathogen‐free fingerling channel catfish, Ictalurus punctatus, and adult zebrafish, Danio rerio, were each separately exposed by immersion challenge to the etiological agent of “columnaris disease,”Flavobacterium columnare (Japanese Collection of Microorganisms 21327 strain). At 24‐h post‐immersion, fish exhibiting a “saddleback” lesion were fixed whole in 10% neutral buffered formalin. Skin samples approximately 5 mm² were excised from both the margin and center of each saddleback lesion as well as from corresponding sites in control, non‐challenged, fish before being prepared routinely for scanning electron microscopy (SEM). Skin samples from control channel catfish and zebrafish had uniform, contiguous epidermal cells with continuous or closely apposed cell margins and well‐defined microridges. Channel catfish skin lesion samples had margins typified by epidermal sloughing and lesion centers that exhibited a multitude of rod‐shaped bacterial cells, approximately 3–10 µm long × 0.3–0.5 µm wide, intermingled with cellular debris across a surface characterized by denuded, strongly ridged, or folded dermal connective tissue. Zebrafish skin lesion samples had a multitude of rod‐shaped bacterial cells and exhibited comparable ultrastructural changes but some lacked scales. These findings are the first published SEM observations of columnaris disease and saddleback lesions in channel catfish and zebrafish and thereby advance our understanding of the ultrastructural characteristics of acute‐stage saddleback lesions and columnaris disease pathogenesis.     

Granulomatous enteritis in rainbow trout (Oncorhynchus mykiss) associated with soya bean meal regardless of water dissolved oxygen level

This study investigated morphological changes associated with soya bean meal‐induced enteritis (SBMIE) in distal intestine (DI) of rainbow trout (Oncorhynchus mykiss) fed a soya bean meal (SBM)‐based diet and exposed to normoxia or hypoxia created by optimal and low water flow rates, respectively. A 28‐day adaption period was followed by a 42‐day challenge period where 600 fish were subjected to dietary challenge and/or hypoxia. Twelve tanks each containing 50 juvenile trout were assigned randomly in triplicate to each treatment. Histopathological and immunohistochemical evaluation revealed pathological features that have not previously been described in association with SBMIE. Vacuolar degeneration of epithelial cells mainly at the base of mucosal folds, epithelial cysts, epithelial dysplasia, necrosis, shedding of necrotic cells, and granulomatous inflammation including infiltration of enlarged, sometimes finely vacuolated or “foamy” macrophages, multinucleated giant cells and increased proliferation of fibroblasts were observed. Acid‐fast bacteria were not detected in enlarged macrophages; however, these cells contained AB‐PAS‐ and sometimes cytokeratin‐positive material, which was interpreted to be of epithelial/goblet cell origin. Hypoxia did not affect the morphological changes in DI. These results suggest that SBM was associated with a granulomatous form of enteritis in DI of rainbow trout regardless of water oxygen level.     

Colonization of Aeromonas salmonicida subsp. masoucida strains in Atlantic salmon (Salmo salar L.) during infection

Aeromonas salmonicida subsp. masoucida (ASM) is classified as atypical A. salmonicida and brought huge economic damages to the local salmonid aquaculture in China. An ASM strain named AS‐C4 was used to investigate the colonization of ASM in Atlantic salmon (Salmo salar L.) by an immersion challenge with the control group (T0, no AS‐C4), group T1 (2.67 × 10⁴ CFU/ml AS‐C4) and group T2 (2.67 × 10⁷ CFU/ml AS‐C4). The numbers of AS‐C4 copies in different fish tissues (gill, intestine, skin, blood, muscle, spleen, liver and kidney) were determined at different time points post challenge using the quantitative real‐time PCR (qRT‐PCR). AS‐C4 were detected in the gill and intestine as early as 0 hr after the challenge both in T1 and T2 groups, suggesting that the gill and intestine were probably the portals of entry of AS‐C4 into salmon. Although AS‐C4 could not be detected in the skin until 24 hr after the challenge in T1 group, it could be detected in the skin as early as 0 hr after the challenge in T2 group, indicating that the skin may also be a portal of entry of AS‐C4 into salmon. AS‐C4 was immediately detected in the blood within 3 hr after it entered the host, suggesting that AS‐C4 successfully invaded the bloodstream of fish. After AS‐C4 colonized the host, it colonized the internal tissues, such as the spleen, liver, kidney and muscle. The results of this study will contribute to the understanding of the pathogenesis of the ASM strains and give a broader understanding of the infection route of ASM in it's host, providing more information for the development of new therapeutic strategies to protect against this pathogen in aquaculture.     

Reconstructing 290 years of a data‐poor fishery through ethnographic and archival research: The East Pacific green turtle (Chelonia mydas) in Baja California,Mexico

Evaluating historical changes in the exploitation of marine organisms is a key challenge in fisheries ecology and marine conservation. In the Eastern Pacific, marine turtles were exploited for millennia before systematic monitoring began <50 years ago. Using ethnographic and historical data, we generated a detailed reconstruction of the East Pacific green sea turtle (Chelonia mydas) fishery in Mexico's Baja California peninsula from 1700 to 1990. Sea turtles from the region's important feeding areas were a staple food source from the earliest phases of human occupation, dating back at least 12,000 years. In contrast with regions such as the Caribbean, small human populations and limited market access resulted in apparently sustainable turtle harvests until the second half of the 20th century. We found that the estimated annual catches between 1960 and 1980 exceeded the estimated annual catches of the previous 250 years by an order of magnitude, leading to the collapse of the fishery and the depletion of the green turtle population. A total ban on sea turtle captures in 1990, comprehensive nesting beach protection, and significant conservation efforts resulted in increases in breeding females on nesting beaches and catch rates in scientific monitoring on main feeding grounds since the early 2000s. This provides a positive outlook for this once‐depleted population segment. Although further research is needed to evaluate current conservation status, we have identified a date, between 1950 and 1960, which can serve as a reliable temporal reference for future evaluations of historical baseline abundance in this region.     

Efficacy of Vibrio anguillarum antigen administered by intraperitoneal injection route in Japanese flounder, Paralichthys olivaceus (Temminck et Schlegel)

Japanese flounder, Paralichthys olivaceus (Temminck et Schlegel), were immunized by the intraperitoneal (i. p.) injection route with formalin‐killed whole cells of Vibrio anguillarum that originated from a diseased fish. Fifty days later, a booster vaccination was given by the same route. Control fish were similarly treated with sterile phosphate‐buffered saline. The efficacy of vaccination was evaluated based on protection against two bacterial challenges and immune responses (both specific and non‐specific). The challenges were performed by i. p. injection with V. anguillarum or V. parahaemolyticus. The results indicated that the vaccinated fish showed higher non‐specific immune activity than the unvaccinated fish. The effects of vaccinations on the phagocytic activity of phagocyte, bactericidal and lysozyme activities were notable, especially on bactericidal activity. Determined by ELISA, antiserum of vaccinated fish displayed high antibody titres. The vaccination conferred protection against V. anguillarum challenge (81.25–93.75% relative percentage survival (RPS)). The RPS was 46.15–53.85% against V. parahaemolyticus challenge, indicating some degree of cross‐protective immunity.     

Formulation of an Alternative Culture Medium for Arthrospira maxima (Spirulina) Based on “Tequesquite,” a Traditional Mineral Resource

Culture media formulation for Arthrospira maxima (formerly designated as Spirulina maxima) production is a constraining factor. Use of synthetic media could be expensive because most of the commercial strains require salinity conditions higher than 20 g/L. In this study, a traditional, pre‐Hispanic mineral resource, known as “tequesquite,” was used as the base for the formulation of an alternative and low‐cost culture medium. Tequesquite is available from outcrop areas located in the basin of the former Lake Texcoco, where A. maxima thrived in pre‐Hispanic times. The effect on the biomass production of different tequesquite‐based formulations, varying N, P, and , was tested and compared with results obtained with Zarrouk's medium (ZM). Growth of biomass in some alternative formulations showed no significant differences compared with ZM. Production in a bubble‐column photobioreactor of the alternative medium reached a maximum of X = 2570.4 mg/L dry weight, compared with X = 2931.4 mg/L dry weight obtained with ZM. The proposed tequesquite‐medium formulation has equivalent N and P concentrations as ZM, but only 50% of NaHCO₃, thus reducing the medium's cost. In addition, it avoids the use of seawater or NaCl to provide the salinity condition required for the adequate growth of Arthrospira.     

Experimental induction of mouthrot in Atlantic salmon smolts using Tenacibaculum maritimum from Western Canada

Mouthrot, or bacterial stomatitis, is a disease which mainly affects farmed Atlantic salmon, (Salmo salar, L.), smolts recently transferred into salt water in both British Columbia (BC), Canada, and Washington State, USA. It is a significant fish welfare issue which results in economic losses due to mortality and antibiotic treatments. The associated pathogen is Tenacibaculum maritimum, a bacterium which causes significant losses in many species of farmed fish worldwide. This bacterium has not been proven to be the causative agent of mouthrot in BC despite being isolated from affected Atlantic salmon. In this study, challenge experiments were performed to determine whether mouthrot could be induced with T. maritimum isolates collected from outbreaks in Western Canada and to attempt to develop a bath challenge model. A secondary objective was to use this model to test inactivated whole‐cell vaccines for T. maritimum in Atlantic salmon smolts. This study shows that T. maritimum is the causative agent of mouthrot and that the bacteria can readily transfer horizontally within the population. Although the whole‐cell oil‐adjuvanted vaccines produced an antibody response that was partially cross‐reactive with several of the T. maritimum isolates, the vaccines did not protect the fish under the study's conditions.     

Extending electronic length frequency analysis in R

Electronic length frequency analysis (ELEFAN) is a system of stock assessment methods using length‐frequency (LFQ) data. One step is the estimation of growth from the progression of LFQ modes through time using the von Bertalanffy growth function (VBGF). The option to fit a seasonally oscillating VBGF (soVBGF) requires a more intensive search due to two additional parameters. This work describes the implementation of two optimisation approaches (“simulated annealing” and “genetic algorithm”) for growth function fitting using the open‐source software “R.” Using a generated LFQ data set with known values, the accuracy of the soVBGF parameter estimation was evaluated. The results indicate that both optimisation approaches are capable of finding high scoring solutions, yet settings regarding the initial restructuring process for LFQ bin scoring (i.e. “moving average,”) and the fixing of the asymptotic length parameter (L_∞) are found to have significant effects on parameter estimation error. An outlook provides context as to the significance of the R‐based implementation for further testing and development, as well as the general relevance of the method for data‐limited stock assessment.     

Assessment of cross‐protection to heterologous strains of Flavobacterium psychrophilum following vaccination with a live‐attenuated coldwater disease immersion vaccine

Bacterial coldwater disease, caused by Flavobacterium psychrophilum, remains one of the most significant bacterial diseases of salmonids worldwide. A previously developed and reported live‐attenuated immersion vaccine (F. psychrophilum; B.17‐ILM) has been shown to confer significant protection to salmonids. To further characterize this vaccine, a series of experiments were carried out to determine the cross‐protective efficacy of this B.17‐ILM vaccine against 9 F. psychrophilum isolates (representing seven sequence types/three clonal complexes as determined by multilocus sequence typing) in comparison with a wild‐type virulent strain, CSF‐259‐93. To assess protection, 28‐day experimental challenges of rainbow trout (Oncorhynchus mykiss) fry were conducted following immersion vaccinations with the B.17‐ILM vaccine. F. psychrophilum strains used in challenge trials were isolated from several fish species across the globe; however, all were found to be virulent in rainbow trout. The B.17‐ILM vaccine provided significant protection against all strains, with relative percent survival values ranging from 51% to 72%. All vaccinated fish developed an adaptive immune response (as measured by F. psychrophilum‐specific antibodies) that increased out to the time of challenge (8 weeks postimmunization). Previous studies have confirmed that antibody plays an important role in protection against F. psychrophilum challenge; therefore, specific antibodies to the B.17‐ILM vaccine strain appear to contribute to the cross‐protection observed to heterologous strain. The ability of such antibodies to bind to similar antigenic regions for all strains was confirmed by western blot analyses. Results presented here support the practical application of this live‐attenuated vaccine, and suggest that it will be efficacious even in aquaculture operations affected by diverse strains of F. psychrophilum.     

Growth response and acquired resistance of Nile tilapia, Oreochromis niloticus (L.) that survived Streptococcus iniae infection

This study determined the growth performance and acquired resistance of Nile tilapia, Oreochromis niloticus (L.) that survived Streptococcus iniae infection. Tilapia were challenged with three doses of S. iniae (8.8 × 10³, 8.8 × 10⁴ and 8.8 × 10⁵ CFU fish^?1 for low, medium and high challenges respectively). Groups of non‐injected and tryptic soy broth‐injected fish were maintained as controls. Significantly (P<0.05) higher mortality (45.0%) occurred in the high challenge treatment than in the low challenge treatment group (29.6%). The medium challenge group had mortality (36.3%) that did not differ significantly from the high or low treatment. Few fish died in the non‐injected and broth‐injected treatments (3.4% and 0.8% respectively). The tilapia that survived S. iniae infection used to assess growth performance were selected from survivors without gross clinical signs of disease. These fish were randomly stocked at a rate of 30 fish into each 57 L aquarium in triplicate and fed to apparent satiation for 8 weeks. No significant differences were detected in weight gain, feed intake, feed efficiency ratio or survival between S. iniae‐survived tilapia and the control treatments following the 8‐week growth performance trial. Following the 8‐week feeding study, tilapia were challenged with 1 × 10⁶ CFU fish^?1 of S. iniae to assess acquired immunity. Mean cumulative mortality was significantly higher (P<0.05) in the control treatments (41.7% for the non‐injected and 43.3% for the broth‐injected fish) than in the low, medium and high challenge treatments (7.4%, 3.3% and 8.3% respectively). Serum protein was significantly (P<0.05) elevated in the S. iniae‐survived tilapia that were subsequently challenged when compared with controls challenged for the first time. Agglutinating antibody titre was significantly higher in the fish in the medium and high challenge treatments, compared with the control fish challenged for the first time. The results suggest tilapia that survive S. iniae challenge without showing overt disease signs performed as well as non‐infected tilapia. Further, the S. iniae‐survived tilapia challenged following the 8‐week growth performance trial gained acquired resistance to homologous S. iniae challenge.     

Ecosystem modelling to quantify the impact of historical whaling on Southern Hemisphere baleen whales

Many baleen whales were commercially harvested during the 20th century almost to extinction. Reliable assessments of how this mass depletion impacted whale populations, and projections of their recovery, are crucial but there are uncertainties regarding the status of Southern Hemisphere whale populations. We developed a Southern Hemisphere spatial “Model of Intermediate Complexity for Ecosystem Assessments” (MICE) for phytoplankton, krill (Euphausia superba) and five baleen whale species, to estimate whale population trajectories from 1890 to present. To forward project to 2100, we couple the predator–prey model to a global climate model. We used the most up to date catch records, fitted to survey data and accounted for key uncertainties. We predict Antarctic blue (Balaenoptera musculus intermedia), fin (Balaenoptera physalus) and southern right (Eubalaena australis) whales will be at less than half their pre‐exploitation numbers (K) even given 100 years of future protection from whaling, because of slow growth rates. Some species have benefited greatly from cessation of harvesting, particularly humpbacks (Megaptera novaeangliae), currently at 32% of K, with full recovery predicted by 2050. We highlight spatial differences in the recovery of whale species between oceanic areas, with current estimates of Atlantic/Indian area blue (1,890, <1% of K) and fin (16,950, <4% of K) whales suggesting slower recovery from harvesting, whilst Pacific southern right numbers are <7% of K (2,680). Antarctic minke (Balaenoptera bonaerensis) population trajectories track future expected increases in primary productivity. Population estimates and plausible future predicted trajectories for Southern Hemisphere baleen whales are key requirements for management and conservation.     

Putative apolipoprotein A‐I,natural killer cell enhancement factor and lysozyme g are involved in the early immune response of brown‐marbled grouper,Epinephelus fuscoguttatus,Forskal, to Vibrio alginolyticus

The gram‐negative bacterium, Vibrio alginolyticus, has frequently been identified as the pathogen responsible for the infectious disease called vibriosis. This disease is one of the major challenges facing brown‐marbled grouper aquaculture, causing fish farmers globally to suffer substantial economic losses. The objective of this study was to investigate the proteins involved in the immune response of brown‐marbled grouper fingerlings during their initial encounter with pathogenic organisms. To achieve this objective, a challenge experiment was performed, in which healthy brown‐marbled grouper fingerlings were divided into two groups. Fish in the treated group were subjected to intraperitoneal injection with an infectious dose of V. alginolyticus suspended in phosphate‐buffered saline (PBS), and those in the control group were injected with an equal volume of PBS. Blood samples were collected from a replicate number of fish from both groups at 4 h post‐challenge and analysed for immune response‐related serum proteins via two‐dimensional gel electrophoresis. The results showed that 14 protein spots were altered between the treated and control groups; these protein spots were further analysed to determine the identity of each protein via MALDI‐TOF/TOF. Among the altered proteins, three were clearly overexpressed in the treated group compared with the control; these were identified as putative apolipoprotein A‐I, natural killer cell enhancement factor and lysozyme g. Based on these results, these three highly expressed proteins participate in immune response‐related reactions during the initial exposure (4 h) of brown‐marbled grouper fingerling to V. alginolyticus infection.     

Protective Immunity of Goldfish Against Ichthyophthirius multifiliis Infection Induced by Different Trophont Vaccine Preparations

Ichthyophthirius multifiliis, commonly called “Ich,” is a protozoan parasite that infects the epidermis and gills of freshwater fish. Here, we used goldfish (Carassius auratus) to determine whether the four vaccine preparations (live trophonts, formalin‐fixed trophonts, freeze‐thawed trophont lysates, and trophont cilial and cell cortical fractions) of I. multifiliis (Fouquet) can elicit resistance of immunized fish against subsequent theront challenge, and whether a relationship exists between in vitro immobilization of theronts in sera or mucus from immunized fish and host protective immunity against the parasite. Experimental goldfish were randomly divided into five groups with five parallel controls, with each group or subgroup consisting of 20 individuals. Each test goldfish was immunized with one of the four Ich vaccine preparations administered by one of the three routes: live trophonts by gavage (Group 1), formalin‐fixed trophonts by injection (Group 2) or by immersion (Group 3), freeze‐thawed trophont lysates by injection (Group 4), and trophont cilial and cell cortical fractions by injection (Group 5). The fish were then challenged by a standard Ich theront challenge on Day 21 postimmunization. For every 10 d following immunization, we tested the in vitro immobilization of Ich theronts by sera or mucus from immunized and control fish. We found that although all control (nonimmunized) and Group 3‐immunized goldfish died following theront challenge, more than half (55–65%) of the immunized fish from Groups 1, 2, 4, and 5 survived. Furthermore, except for the fish from Groups 3 and 4, the number of mean days to death in each test group was significantly higher than that in the respective control. These results indicate that goldfish immunized by injection or by gavage with any of the four vaccine preparations gained resistance to Ich infection. Further analysis indicated that this protective immunity was closely associated with the in vitro immobilization of Ich theronts by fish sera or mucus.     

Impacts of stock enhancement strategies on the effective population size of Murray cod,Maccullochella peelii,a threatened Australian fish

Abstract Murray cod, Maccullochella peelii (Mitchell) is an iconic Australian species endemic to the Murray‐Darling Basin (MDB) of inland south‐eastern Australia. Murray cod has been a valuable food source and supported a large commercial fishery throughout much of the 20th century. Over‐fishing and habitat destruction have resulted in significant declines in Murray cod populations throughout much of its range. Since the early 1980s, large numbers of Murray cod have been stocked into waterways to support both recreational fishing and conservation efforts. In this study, the likely impacts of past and current stocking practices on genetic diversity of Murray cod were modelled and new strategies to maximise genetic diversity in stocked populations are explored. The results suggest that a large, well‐managed breeding and stocking programme could help maintain genetic diversity of Murray cod across the MDB. In catchments within the MDB where the effective population size is very small, a well‐designed stocking programme, following strict guidelines for numbers of families reared and number of individuals maintained per family, could increase genetic diversity in a few generations.