Trends in Fisheries and Aquatic Animal Health

Climate change is affecting biodiversity and overall system functioning of all the worlds’ oceans. Over the past decades, significant amount of evidence has accumulated which allow us to decipher its effects on the Adriatic Sea. Investigations of fish communities in its eastern part showed us that it has undergone a significant biodiversity changes which are dominated by the influx of alien fishes, distributional shifts of native fishes and community-level changes of native populations of fishes. These changes have profound influence on fishery and aquaculture of the eastern Adriatic Sea. Beside current state, potential future scenarios which will affect its fish and fisheries are reviewed.

Eastern Adriatic countries (ecoregion Dalmatia 419) have a unique array of endemic freshwater fishes. Our knowledge about the diversity of its freshwater fishes is still incomplete, many new species having been described only in recent years. It is widely held that fish biodiversity constitutes a natural resource that is valuable not only economically, but also in terms of culture and aesthetics, science and education. We have reviewed the characteristics of fish biodiversity in the eastern Adriatic countries (Slovenia, Croatia, Bosnia and Herzegovina as well as Montenegro), with a special emphasis on Croatia. Endemic species are found in the river Soča, Istria Mirna River, the region of Lika and in the Krka, Cetina, and Neretva River basins, in the Moraca and Skadar Lake. Usually, a single catchment supports between 6 and 10 species. Out of the 52 European threatened freshwater species, 28% occur in the eastern Adriatic, making this area a hotspot for threatened freshwater fish. Conservation management of these resources should be considered critical by all the governments involved. The area of occupancy of endangered freshwater fish is declining and if this does not change and if the loss of species continues at the current rate, the opportunity to conserve many of the remaining species will vanish. The speciation processes of endemic species started here about 5 million years ago, but the present-day distribution patterns essentially started to be established in the Pleistocene. A special mechanism for surviving drought has evolved in these populations and in general fish in the karstic area have become very hardy; however, negative anthropogenic effects have changed much of this evolution. An overview of endemic behaviour and some examples of patterns that undermine normal existing mitigation measures are provided. Human threats to global freshwater fish biodiversity fall into five categories: over-exploitation; water pollution; flow modification; destruction or degradation of habitat; and invasion by exotic species. Combined and interacting influences on fish biodiversity are now generally well known and have been exacerbated by climate change. We believe that knowledge of these threats is insufficiently incorporated into the development of water resources development and requires wider dissemination.

In addressing the issue of Mediterranean aquaculture, and having the fact that the aquaculture sector is partly associated with the relevant European Common Fisheries Policy, the study provide both global and European circumstances relevant for current state, growth target and future challenges. Marine aquaculture, in the Medterranean has shown a rapid growth in 1990s, and by the time became an important source of seafood, employment and income. However, it has not progressed significantly over the last decade, due to several factors that influence performance of the main fish species production. Replacement with ingredients from plant origin has influenced FCR, presence of mycotoxins in feed and micro ingredient deficiency Many breeding, health and welfare issues still remain unresolved. Lack of spatial planning on the integrated principles, access to quality fish feed, eggs and fry, has restricted aquaculture in some developing countries. Complicated administrative procedures related to national and regional environmental regulations were constraining aquaculture development in many EU-Mediterrenan states. Fragmented approach to marketing of mariculture products requires a cooperation of different actors across the Mediterranean. Vision for 2030 has projected doubling finfish production. However, for such a development a set of practical solutions are needed in production, governance, cooperation, policy management, market development, and spatial planning. If aquaculture tends to meet its goals, it must improve production models and environmental performances. It is expected that future production economy may take advantage of diversifying species and combining land based recirculating aquaculture systems (RASs) with more open sea farming by employment of more robust cage installations. Integration with non-fed organisms is a promising option in achieving better economic and environmental benefits.

A detailed picture of fisheries issue, within the context of the Mediterranean Sea, in order to investigate possible challenges and opportunities in the framework of the reformed Common Fishery Policy (CFP) is presented as invited speech. The Mediterranean Sea has lots of diverse benthic communities in the coastal area that imply high number of species and complex trophic relationships. Since ancient times fisheries were very important on the Mediterranean, and nowadays it’s even more crucial due growing human population. A majoritie of fisheries in that coasta, shallow area is small-scale, characterized by multi-purpose and multi-gear fleet operating on seasonal basi, with multi-species catches and extremely heterogeneous landing places and marketing. Thus, scientific research of small-scaled fisheries is a particularly complex. Moreover, the facts regarding serious overfishing of most Mediterranean stocks demands urgent reforms of the management measures aiming to guarantee the sustainability of resources, particularly in comparison with the improvement observed in NW Atlantic seas. According to the new, reformed CFP, all European fish stocks should be brought to a state where they can produce at maximum sustainable yield (MSY) by 2020 at the latest. The sustainable exploitation should be achieved through multiannual plans (MAPs) reflecting regionality and the specificities of different fisheries as it is established as new CFP objective. Creation of MAPs should be based on scientific, technical and economic advices with included conservation measures for restoring and maintaining Mediterranean fish stocks above the determined MSYs. Since, in mixed Mediterranean fisheries, small-scale fishers landed more than a hundred commercial species and each one has specific MSYs, it is extremely difficult to regulate the fishing mortality independently for each species. Moreover, population dynamics of all Mediterranean species is also influenced by the recent environmental and oceanographic changes provoked by global climate change impacts. To really improve state of Mediterranean resources and maintain fisheries as economic activity, many different contrasting socioeconomic and ecological interests need to be confronted. Further on, recent demands for drastic reductions of fishing effort and consequently reduction of landings, based on new CFP objectives, requests for socially unacceptable management measures. For sure, actively involving scientists, fisherman and policy makers in fisheries management can minimize those tensions.

Foodborne transmission of antibiotic resistant strains of bacteria from contaminated food has been recognized as an important hazard for human health in the past few decades and pathogenic strains of aquatic bacteria have long been considered as serious zoonotic hazards. Relatively low and competitive price of fish meat, the lack of religious and cultural barriers and the nutritional quality are the main reasons for the fact that fish meat is very attractive for consumers worldwide, so the measures to preserve the safety of fish meat are very important issue. The widespread consumption of different antimicrobial drugs in aquaculture could lead to the evolution and transmission of resistance determinates from fish to humans via the food chain. The link between the utilization of such drugs and the existence of antibioric resistance in infective either in commensal microorganism which can be found in fish and in aquatic environment and also residues of those drugs in fish due to improper utilization of veterinary drugs is discussed in this manuscript. The need for prudent use of antibiotics, particularly those which are used in human medicine is highlighted. The aim is also to point toward the present difficulty in the aquaculture management and to show the possible ecological and economical impacts. Monitoring and recording of occurrence should be the main operations in the upcoming years which should moot questions of how to make better and put into actions the established directives.

In aquaculture, stress related disease problems which are leading to serious limitations in sustainability of the sector are of major importance however, stressors in aquaculture are unavoidable. In terms of characteristics of interaction of stress and health in aquaculture, stress physiology has been the center of attention. In fish, the physiological stress response to stressors causes primary response involving neurohormonal stimulation, resulting in an increase in corticosteroid and catecholamine secretions. In turn, these primary effects cause a number of physiological changes known as a secondary response. Tertiary stress response involves the effects on immunocompetence and potential susceptibility to diseases. The effects of stress on the fish physiology have been extensively studied for many years. It is known that acute stress can have beneficial effects in short-term, however, chronic stress hinders the immune system from functioning in teleost fish. Thus, the recent approach to explain the negative effects of stress, allostasis theory and allostatic load is presumed, concerning with how stability of the body’s is achieved through change. The correlation between the stressors and disease was reported for various fish species cultured and the diseases. To characterize the stress response, the immunocompetence state may provide better approach to understand the disease emergence. Stress response measurements are mainly based on the levels of cortisol nevertheless, it might be better to characterize the stress response with an index of immunological parameters and/or allostatic load.

Fish are regarded as valuable organisms in monitoring aquatic ecosystems. They are established as indicator organisms and widely used in both laboratory studies and ecotoxicology. A range of biomarkers are developed for monitoring effects of xenobiotics on fish. Histopathology is classified as an important biomarker in terms of toxicological significance and highly relevant when chronic or sublethal pollutants are present in the water. In this chapter, a short review of histopathological methods is given, with basic guidelines for conducting field studies. The main focus is on different methods for quantifying alterations, namely: semi-quantitative scoring system, histomorphometry and stereology. Advantages and shortcomings of each method are briefly discussed.

Cyanobacteria are grouped together with phytoplankton as primary producers in aquatic environments. These organisms are very diverse and under favorable conditions, their biomass increases dramatically, leading to blooms. Cyanobacterial blooms in aquatic environments are a well known global phenomenon, largely as a result of anthropogenic pressures, such as increas-ing nutrient inputs from catchment areas or climate change. Especially, planktonic cyanobacteria can thrive in surface waters and cause several adverse effects on aquatic organisms due to variations in pH, blocking light from entering the water and oxygen deficiency as a result of respiration at night. Moreover, they also produce toxins, called cyanotoxins, which can pose harmful effects on organisms in every trophic level; phytoplankton, zooplankton, invertebrates, fish, birds and also mammals. Cyanotoxins comprise of very diverse chemical compounds with several adverse effects on organisms. Considering the diversity of cyanotoxins, we chose two cyanotoxins, microcystin and cylindrospermopsin, since there are relatively more data about their toxic effects on fish, and also the former has a worldwide distribution and the latter is an emerging toxin with an extending geographical range. Together with the other adverse effects on fish, microcystins and cylindrospermopsin could cause oxidative stress and histopathological changes which we focus on and review in detail in this chapter.

Inland saline aquaculture in salt-affected areas presents an opportunity for income modification and a potentially productive use of land that cannot support traditional agriculture production and the investment levels are characteristically low. Such systems need to be developed in a manner that both prevents further degradation of agricultural land and provide opportunities for an alternative and sustained economic growth of rural communities. Most central areas of Iran are at high risk of salinization through surface water. Using saline groundwater for aquaculture production is a potential adaptive use of these otherwise degraded resources. Expansion of aquaculture in these areas is limited by some factors such as shortage of suitable sites and strict environmental regulations. These limitations, with an abundance of salt-affected land and water resources, have led to the logical progression of investigating the suitability of these resources for aquaculture. Rainbow trout, which could well adapt to rapid changes in salinity, has been promoted as a potential candidate for aquaculture in these areas. Through using suitable production systems well-set to climate conditions, trout desert farming using brackish water could be a profitable method to develop inland aquaculture in Iran.

The total amount of crustaceans, mainly the decapods, from fishery and culture consist a serious part of the global fisheries and aquaculture production. Richest and poorest countries are included between the top ten shrimp-producing countries in the world. The management of some shrimp fisheries is effectually carried out and provides the potential profits of fisheries’ management. Several problems are connected with shrimps culture, like the increasing demand for this seafood, growing number of unfamiliar diseases, a narrow capability to front the several diseases, inadequate post-harvest treatment of “wild” organisms and an increasing legislative charge regarding the marketing of live animals, indicating a clear warning for the future sustainability of this cultivation.

Rainbow trout (Oncorhynchus mykiss) is a highly commercial sport and market fish. Rainbow trout feed formulations are using fish oil, fish meal, grains and other in-gredients. In recent years the amount of fish meal has been reduced to less than 50 percent. This was achieved by using alternative protein sources such as soybean meal. The aim of this study was to assess the changes of intestine histology of rainbow trout fed three different iso-energetic and isoproteic diets with a partial substitution of fish meal and fish oil with vegetable protein and vegetable oil. The goblet cell number per μm of intestinal fold appeared to not be affected by diet, while goblet cell diameter appeared smaller in rainbow trout fed a diet of 31% organic vegetable protein. Rainbow trout fed the above diet had a smaller submucosa layer. Rainbow trout fed a diet of 36% vegetable protein and 6% vegetable oil had smaller intestinal folds, but the brush border height and muscular layer width were unaffected by the diet. Changes in the rainbow trout intestinal histology following a single meal were studied. Intestinal samples were taken before feeding and at 6 h and 12 h after feeding. At 6 h after feeding, the protein synthesis rate in trout is in its peak and the digestion process is in progress. Goblet cells then secrete their mucous and their size is decreased. The similarity in the size of the goblet cells before feeding and at 12 h after feeding sugest that rainbow trout should be fed twice per day and that the second feeding should take place between 6 and 12 hours after the first feeding. In fish intestine the goblet cells’ post-prandial changes may occur in response to a single meal because they have a potential role in the digestion process. Research on how dietary composition and, in particular, plant ingredients modify intestine and liver histology over time and whether fish can adapt to plant protein and oil feeding are very important for a sustainable fish supply.

Climate change, pollution, overfishing and the periodic appearance of the sponge disease, dramatically reduced the stock of sponges, the number of species and the diversity of their forms. Demand continues to grow despite their high prices (150 euros/kg). Price depends on type, quality, necessary processing and geographical origin. The possibility of producing secondary metabolites & collagen from sponges makes them a valuable source for the production of raw materials of high added value. An experimental culture was performed in an integrated aquaculture fish production unit in Larymna (Greece) on ropes between fish cages (arranged vertically), on iron frames placed 0.5 m above the bottom (arranged horizontally) and in onshore tanks. Thus far results from the sea experiments (vertical and horizontal arrangements) have been encouraging, while those from the onshore facilities have been less so. Three experiments were performed with two species of sponges in order to develop a suitable method of sponges’ mariculture in parallel with fish farming with the following objectives: (a) to study the robustness of the sponges, (b) to investigate the method of harvesting in order to ensure sustainability of their biotopes, (c) to investigate the modes of transport from the harvesting areas to the experimental unit, (d) to examine a biological decontamination technology in closed bays and protected areas thanks to the high filtration capacity of the sponges.

The presence of the blue crab Callinectes sapidus has been recorded late in the 2000s in the lagoons of Amvrakikos Gulf. Ninety four individuals from Pogonitsa lagoon (Amvrakikos Gulf, Western Greece) have been observed and measured during August 2016. Based on biometric and biological features, these crabs were mature while most of the females were ovigenous in various eggs age since extrusion. The estimated ages of the animals and the fecundity were in agreement with those that are reported in native and/or in well-established regions of species. The population of the blue crab seems to be increasing and can be considered as established in Pogonitsa lagoon as well as in other lagoons of Gulf.

Cyprinid Herpesvirus 2 (CyHV-2) is an emerging pathogen which can cause huge economic losses in fish farming worldwide. This study describes a disease outbreak in crucian carp (Carassius carassius), reporting for the first time a CyHV-2 infection in Piedmont (Italy), since it has never been described in this area. Our findings also highlighted that both Aeromonas hydrophila and Aeromonas sobria have been isolated in association with CyHV-2; we have speculated that motile Aeromonas spp. and CyHV-2 could be regarded as a potential “infectious pathogenic-complex”. However, this evidence-based hypothesis must be corroborated by further studies and investigations. In our opinion, it is very important, through experimental studies and case report, to determine the impact of CyHV-2 on Carassius carassius, in order to establish proper commercial regulation and biosecurity measures to prevent the introduction and widespread of diseases.

Infectious Hematopoietic Necrosis (IHN) and Viral Haemorrhagic Septicaemia (VHS) are two systemic infections of several species of salmonids; whose reporting is mandatory in accordance with Directive 67/1991 EC. In order to obtain and preserve the free status at farm level, the Italian legislation (D.L.vo 148/2008) adopted a surveillance program involving all freshwater farms raising salmonids to be released on watercourses. This study provides a description of the epidemiology of IHN and VHS in the Piedmont Region, during the period 2000-2015. In fact in the last 16 years the surveillance was extended to all fisheries. We firstly described the disease distribution by year and by geographical area., then the potential role of several farm charcteristics was tested using unvariate and multivariate analysis.

Fish, Tinca tinca were exposed to chronic low levels of zinc (2 mg/L, 10% of 96h LC50) for 3, 10 and 20 days respectively and its hematological parameters were studied. It was found that Clotting time (CT), Thrombocyte count (TC), Red blood cell (RBC) counts, Hematocrit (Hct), Hemoglobin (Hb), Sedimentation rate (SR), White blood cell (WBC) count and Leucocrit (Lct) did not show a significant difference in 3 and 10 days chronic exposures. However, a significant increase in Clotting time, Sedimentation rate and White blood cell (WBC) count and significant decrease in Thrombocyte count and Hemoglobin were observed in 20 days exposure (P<0.05).

Artificial reefs are to be used as a tool in fisheries management in worldwide since long time. Fishing practices in artificial reef areas should also be operated with a management model as it is in the other fishing zones. Unmanaged artificial reef system may be more harmful than its profits. Acoustic telemetry can be an extremely effective tool to understand the home range and movement models of the fish species for data of management fisheries in artificial reef areas. Acoustic telemetry technology has an important potential to determine strategy in fisheries management around artificial reefs and in construct more efficient artificial reef project.