Presentation on theme: "Dr. Waheed M Emam Prof. of Marine Biology INTRODUCTION goal of fisheries management is to conserve the stock of different fish species for future generations."— Presentation transcript:
Dr. Waheed M Emam Prof. of Marine Biology
INTRODUCTION goal of fisheries management is to conserve the stock of different fish species for future generations. pollution, coastal development and other human activities have lead to the degradation and destruction of spawning and the natural habitats of many fish species.
INTRODUCTION The reduction of spawning stocks below a threshold by fishing is called recruitment over-fishing. It prevents many population from recovering to previous levels of abundance. Intensive fishing with poorly selective gears may alter the habitat, and affect biodiversity, community structure, species composition and abundance of both target and other species within the food web.
INTRODUCTION The great majority of fishery production occurs within 200 miles of land which roughly corresponds in many areas to the limits of the Exclusive Economic Zone (EEZ). Marine fishery resources are highly susceptible to the impacts of human activities.
INTRODUCTION The effective fishery management required: 1- an assessment of fish stock 2- a better understanding of the ecological susceptibility of a resource to forces leading to environmental change. 3- to know the kinds of responses likely to occur in a population of a species, hence in its ecosystem as a whole, for example, redistribution (to avoid an adverse environmental condition); changes in growth rate, mortality rate, fecundity and recruitment.
INTRODUCTION The basic purpose of fish stock assessment is to provide advice on the optimum exploitation of aquatic living resources such as fish and shrimp. The optimum exploitation level (E0.5) achieves in the long run the maximum sustainable yield (MSY)in weight from the fishery. The major economic gains from harvesting the marine resources must come from ensuring that harvesting capacity does not exceed the capacity of the resource to sustain this harvest while reproducing itself.
INTRODUCTION The Mediterranean system is formed of basins includes semi-enclosed seas ranging from: - Atlantic water masses in the Western Mediterranean to slightly hypersaline warm-temperate water masses in the Eastern Mediterranean (Levantine basin), hyposaline waters in the Black Sea. * The Mediterranean sea includes a large number of habitats with diverse stocks and species. * It is highly affected by various activities of populations living in its coastal states.
INTRODUCTION The present study aims to give more information about the strategy plan that can be applied for the management of Mediterranean fisheries including the Egyptian fisheries.
CONTENTS 1- CHARACTERISTICS OF THE MEDITERRANEAN SEA 1.1.Geographical setting 1.2. Water circulation 1.3. Water Balance 1.4. Chemical Characteristics 1.5. Primary Productivity 1.6. Zooplankton 1.7. Benthic Fauna 1.8. Pollutants
1- CHARACTERISTICS OF THE MEDITERRANEAN SEA 1.1.Geographical setting SA= 2.5 million km2. Av Depth= 1.5 km TV= 3.75 km3., West Basin=0.85 km2 Lmax= 3800 km. Wma= 900 km Gibriltar strait: 1.5 km wide, 290 m deep, Sicily Strait: 150 km wide, 800 m deep
1- CHARACTERISTICS OF THE MEDITERRANEAN SEA 1.1.Geographical setting
The Mediterranean Sea lies between Europe, Asia and Africa. It covers without the Black Sea about 2.5 million km2. Its average depth is about 1.5 Km. Its water volume is 3.7 million km3. Its maximum length from Gibraltar to Syria is about 3,800 km. Its maximum distance in the north-south direction from France to Algeria is about 900 km.
1- CHARACTERISTICS OF THE MEDITERRANEAN SEA 1.1.Geographical setting The Mediterranean Sea is connected with: 1- the Atlantic by the Strait of Gibraltar (1.5 km wide and 290 m deep), 2- with Marmara Sea by the Dardanelles (between 450 m and 7.4 km wide and 55 m deep), 3- with the Red Sea by the Suez Canal (120 m wide and 1200 m deep).
1- CHARACTERISTICS OF THE MEDITERRANEAN SEA 1.1.Geographical setting The Mediterranean sea has two major basins, western and Eastern that are separated by the Strait of Sicily (150 km wide and about 800 m deep). The surface area of the western Mediterranean is about 0.85 million km2. western Mediterraneanbasin includes the Alboran Sea, the Algerian Basin, the Algero-Provencal basin, the Balearic Basin, Ligurian Sea, Gulf of Lion, and the north and west Tyrrhenian Basins.
1- CHARACTERISTICS OF THE MEDITERRANEAN SEA 1.1.Geographical setting The Eastern Mediterranean (about 1.65 million km2) includes the Adriatic Sea, the Ionian Sea, the Aegean Sea and the Levantine basin. The eastern continental shelf is very narrow, not more than 8 km wide, except off the Nile Delta where 200 m depth contour lies 60 km offshore.
1- CHARACTERISTICS OF THE MEDITERRANEAN SEA 1.1.Geographical setting The major Mediterranean rivers (Ebro, Rhone, Po and Nile). These rivers account for over 50 million tons annually of sediment injected into the system.
1- CHARACTERISTICS OF THE MEDITERRANEAN SEA 1.2. Water circulation The Atlantic water moves eastward as a surface along the North African coast from Gibraltar to strait of Sicily, where it enters the Ionian Sea basin of the eastern Mediterranean. It continuous eastward to reach the Levantine basin through the strait of Crete to the Egyptian coast where it finally entrapped in the large Marsa Matrouh anticyclone gyre. The return of Mediterranean water is by way of Levantine intermediate water and Mediterranean deep water flowing from east to west and spilling over the sill of Gibraltar into the deep Atlantic. Such intermediate and deep water is produced by very pronounced evaporation processes which gradually transform surface water with salinity above 36 %o into denser water with salinity of 38.4 %o or more. The estimated residence time for Mediterranean waters is 80 years.
1- CHARACTERISTICS OF THE MEDITERRANEAN SEA 1.2. Water circulation
1- CHARACTERISTICS OF THE MEDITERRANEAN SEA 1.3. Water Balance The total input water to the Mediterranean Sea is about m3s through the inflow of Atlantic water from the Strait of Gibraltar (l m3s-1), 2- through the Dardanelles from the Black Sea and Sea of Mormara ( m3s-1), 3- through the rivers run off (7 300 m3s-1), 4- through precipitation ( m3s-1). * On the negative side of the balance there is outflow of water to the Atlantic ( m3s-1 ), to the Black Sea ( m3s-1 ) and by evaporation ( m3s-1).
1- CHARACTERISTICS OF THE MEDITERRANEAN SEA 1.4. Chemical Characteristics Mediterranean sea does not have a chemistry of its own. Since residence time of the Mediterranean waters is about 80 years, most of the elements have plenty of time to tour the Mediterranean sea. A fundamental characteristic of Mediterranean water is its impoverished nutrient concentration. No deep nutrient rich Atlantic waters take part in the Mediterranean circulation. the upper 150 m of the Atlantic water provide replacement for the Mediterranean Sea. the only increase in the concentration of nutrients is due to river input and agricultural run off or pollution. phosphate values in the Mediterranean vary from 0.l to 0.5 ug L-1. The eastern Mediterranean has a smaller range of phosphate content than the western.
1- CHARACTERISTICS OF THE MEDITERRANEAN SEA 1.5. Primary Productivity The major productivity of the Mediterranean sea is low. It ranged from (5-150 mg C/m3 /24 h). the lowest values are in the south eastern basin (5-30 mg C/m3 /24h). The primary productivity in the central parts of the Mediterranean sea and in many of the coastal areas away from the influence of major rivers is rather low. The principal nutrients, such as nitrogen and phosphorus, are often limiting. Of the main source of the low nutrient content in the Mediterranean Sea is the surface Atlantic waters, which are low in nutrients. The continental shelf of the southern Mediterranean is less productive than the shelf of the northern Mediterranean where a number of rivers pour nutrients into the sea.
1- CHARACTERISTICS OF THE MEDITERRANEAN SEA 1.6. Zooplankton The general trends of zooplankton distribution (in which the Mediterranean areas are not affected by continental enrichment) show an increasing abundance toward the south-west end of the western basin.
1- CHARACTERISTICS OF THE MEDITERRANEAN SEA 1.7. Benthic Fauna The Mediterranean Sea is very rich in the variety of its benthic communities, although it is relatively poor in the quantity of organisms produced. Its fauna is characterized by many endemic species and is considerably richer than the Atlantic coasts. The percentage of endemic species is very high for the sessile or sedentary groups such as ascidians (50.4 %), sponges (42.4%), hydroids 27.1 %), echinoderms (24.3 %), decapod crustaceans (13.2 %) and demersal fishes (10.9 %).
CONTENTS 2- MEDITERRANEAN FISHERIES 2.1. Fishing gears Purse seine Trawls and dredges Baited hooks and line gears Gill nets Trammel nets Traps and pot 2.1. Fish Production
2- MEDITERRANEAN FISHERIES 2.1. Fishing gears Fishing gears used in the Mediterranean fisheries can be classified as active or static/fixed. - Active gears are those which involve motion and include trawls and dredges which are towed and purse seines which surround the school of fish. - Static gears are those which are anchored or fixed and depend on the movements of the fish to come into contact with the gear like longlines, gill nets, trammel nets, pots, and traps.
2- MEDITERRANEAN FISHERIES 2.1. Fishing gears Purse seine A purse seine is an active encircling gear, supported by floats, which is used to catch schooling fish in the upper part of the water column (pelagic species). The depth and length of the net can be considerable, more than 100 m deep and 500m long in the case of large tuna purse seiners. Once the net has been set around the school, the net is 'pursed', Closing the bottom as the net is hauled and trapping the fish.
2- MEDITERRANEAN FISHERIES 2.1. Fishing gears Trawls and dredges Trawls and dredges are active gears towed by one or a pair of fishing vessels. Various types of trawls are used to target demersal species from relatively shallow inshore waters to depths of more than 1000 m, as well as schooling or pelagic species in the water column. Size selectivity of fish is a function of the mesh size used in the cod-end of the trawls.
2- MEDITERRANEAN FISHERIES 2.1. Fishing gears Baited hooks and line gears I nclude handlines, electric reels for fishing in deep water and longlines. In the case of handlines and electric reels, the terminal tackle consists of a lead weight and a spall number of hooks, usually not more than six. Longlines consist of a mainline to which is attached branch lines at regular intervals supplied with hooks. Types of longline: bottom, semi- pelagic, vertical and pelagic. Bottom longlines target demersal species such as sea bream and cod. The semi-pelagic longline has floats which lift the mainline off the bottom, and is used for species such as hake. Vertical longlines are often used for very deep water species, pelagic or drifting longlines are mainly used to target large pelagic fish (tuna, shark and billfish) with hooks suspended in the water column.
2- MEDITERRANEAN FISHERIES 2.1. Fishing gears Gill nets Gill nets are single sheets of netting, usually monofilament, with a weighted footrope and a headrope with floats, which are usually fished anchored on the bottom to catch demersal and benthic fish.
2- MEDITERRANEAN FISHERIES 2.1. Fishing gears Trammel nets Trammel nets consists of three sheets of netting: an inner small mesh panel (e.g. 80 mm stretched mesh) between two large mesh outer panels (e.g. 140 mm stretched mesh). While some fish may be gilled or wedged in the smaller mesh netting, larger fish will push the small mesh netting through the larger mesh, forming a pocket in which they are tangled. Trammel nets are widely used for species of flatfishes, sea breams and cuttlefish.
2- MEDITERRANEAN FISHERIES 2.1. Fishing gears Traps and pots Traps and pots are passive capture gears. Bait may or not used as an attractant. Traps have one or more openings and chambers in which the catch remains until the gear is hauled. These gears are generally thought to be highly selective.
2- MEDITERRANEAN FISHERIES 2.2. Fish Production The Mediterranean total annual fish production was 1.4 million tons in It seems unlikely that any under-exploited stocks have not been left in the Mediterranean, although in certain years and seasons there may be a sudden increase in abundance of some small pelagic stocks, often as a result of some temporary environmental condition. It is only in Morocco that a substantial industry has been built up using marine fish (from Mediterranean Sea and Atlantic Ocean) as the main resource for large scale industrial processing and export of fish products.
2- MEDITERRANEAN FISHERIES 2.2. Fish Production FAO fisheries statistics consider almost 200 species or group of species in their Mediterranean database. According to Scientific Advisory Committee (SAC) of the General Fisheries Commission for the Mediterranean (GFCM) only eleven species account for 50 % of the total Mediterranean landings. They represent shared and highly migratory stocks in the Mediterranean Sea and have high economic values.
2- MEDITERRANEAN FISHERIES 2.2. Fish Production These species were: Demersal species (5) European hake (Merluccius merluccius) Red mullet (Mullus barbatus) Striped red mullet (Mullus surmuletus) Blue whiting (Micromesistius poutassou). Blue and red shrimp (Aristeus antennatus) Small pelagic species (3) Anchovy (Engraulis encrasicolus). Sardine (Sardina pilchardus). Sardinella (Sardinella aurita) Large pelagics (3) Blue tuna (Thunnus thynnus). Albacore (Thunnus alalunga). Swordfish (Xiphias gladiusi).
2- MEDITERRANEAN FISHERIES 2.2. Fish Production
2- MEDITERRANEAN FISHERIES 2.3. Fisheries of Egypt Problems of Egyptian Fisheries a. Shortage of Nile flood b. Overfishing c. Pollution Change in Egyptian Fisheries Fishing Gears Main Fishing Areas
2- MEDITERRANEAN FISHERIES 2.3. Fisheries of Egypt Problems of Egyptian Fisheries a.Shortage of Nile flood The Mediterranean Egyptian Fisheries was affected by the construction of the Aswan High Dam. The extruded flood water into the Mediterranean decreased from 43.5 Xl012 m3 (before the dam) to 4.4 x 1012 m3. The coast salinity increased by about 2.3 mg/l The coast and transparency was increased from 10 m to 20 m. The silicates and phosphates was extremely decreased and this causes great reduction in phytoplankton to become 100 times less. The abundance and size of different aquatic populations, particularly sardine were decreased.
2- MEDITERRANEAN FISHERIES 2.3. Fisheries of Egypt Problems of Egyptian Fisheries b. Overfishing The main reasons for overfishing are: The continuous use of trawling in the area between Abu Qir and Damietta. The use of efficient nylon nets in restricted area. The haphazard use of purse seine, particularly at day time. The currently used Italian trawling nets with narrow mesh size in the cod end. The use of beach seine in certain areas, despite its illegal use.
2- MEDITERRANEAN FISHERIES 2.3. Fisheries of Egypt Problems of Egyptian Fisheries c. Pollution Continuous drainage of industrial and other wastes into the Mediterranean coast at Max and Abou Qir had affected mainly the fish larvae and also the abundance of adult fish. Some species such as grey mullets have been greatly influenced. The pollution through the lake sea connections hindered the entrance of fry into the lake and adult fish from the lakes to the sea for spawning.
2- MEDITERRANEAN FISHERIES 2.3. Fisheries of Egypt Change in Egyptian Fisheries The annual catch during the period from was subjected to continuous decrease from tons to about 12000s (with annual average of tons). This significant decrease was mainly caused by the decrease in sardine catch which amounted from tons to 1000 tons during this period. Meanwhile, the shrimp catch was decreased from 7000 tons to About 60 % of the landed catch in this period was caught by the trawling net. An average annual catch of about 8000 tons was landed during the period from The trawling catch constituted about 66 % of the total annual catch. The noted decrease was due to the actual drop in the pelagic fisheries, mainly sardine.
2- MEDITERRANEAN FISHERIES 2.3. Fisheries of Egypt Change in Egyptian Fisheries The annual average catch greatly increased during the period from and reached tons. Meanwhile, the trawling catch decreased to about 46 %. The sudden increase in the average catch was relevant to the use of purse seine nets on large scale, attracting the pelagic fish which flourished in the more transparent water in the period of no flood. The period from was characterized by significant increase in the Mediterranean production to about tons. The annual catch was also increased to reach tons during This was followed by sharp reduction in fish catch to about and tons during 2000 and 2001 respectively. The total annual production of shrimps, sardines and sea bream represented about 33 % of the total annual fish catch.
2- MEDITERRANEAN FISHERIES 2.3. Fisheries of Egypt Fishing Gears a.) The Italian trawling net is the main gear and produces 45 % of the total fish catch during the period b.) The purse seine net (Shanchaulla) is the second main gear and produces about10 % of the total fish catch during the same period. The fishing season of purse seine extends for 9 months (from March - November). The maximum catch of purse seine could be taken in June and July. The main catch of this gear is sardine (78 %). c.) The beach seine is considered producers to about 20.5 % of the total fish catch during d.) The long line produces about 3.4 % of the total annual fish catch during e.) The gill and trammel nets frequently operate in the coastal zones and produces about 3 % of the total fish catch during f.) Other types of gears and about 17 % of the total fish catch is produced by using them.
2- MEDITERRANEAN FISHERIES 2.3. Fisheries of Egypt Main Fishing Areas
a.) The Eastern area, extends 180 km from Port Said to Rafah, with total area of about feddan, with rocky bottom except infront of EI-Arish. b.) The Middle area, extends 300 km from Port Said to Alexandria and has feddan total area. The bottom is muddy or silty muddy, suitable for trawling where 80 % of fishing effort takes place. It includes five landing sites (Port Said, Demietta, Borullous, Rosetta and Abou Qir). Demietta landing site is the most important one and contributed by about 28 % of the Egyptian Mediterranean landings. c.) The Western area, from Alexandria to EI-Salloum (450 km), with feddan total area. Rocky bottom, not favourable mostly for trawling. Fishing Boats used trammel net, gill nets and long line. In summer, large boats are used in trawling on suitable grounds in Marsa Matrouh.
2- MEDITERRANEAN FISHERIES 3- SPECIAL PROBLEMS IN FISHERY RESOURCES IN THE MEITERRANEAN SEA The General Fisheries Council for the Mediterranean (GFCM) Definitions: 1- shared stocks : stocks of fish that migrate across the Exclusive Economic Zone (EEZ) boundary of adjacent or opposite coastal states. 2- Straddling stocks : stocks which occur in both within EEZ and in an area beyond and adjacent to EEZ. 3- Highly migratory: stocks include marine species whose life cycle includes lengthy migration, usually through EEZ of two or more countries as well as into international waters (this term is used to denote tuna and tuna-like species, marlins and swordfish).
3- SPECIAL PROBLEMS IN FISHERY RESOURCES IN THE MEITERRANEAN SEA Problems of Shared and Straddling species: 1- Reasons : Interference of EEZs of 2 or more countries. Lack of co-ordination between management authorities responsible for exploitation of shares species. Lack of information on shared and straddling stocks
3- SPECIAL PROBLEMS IN FISHERY RESOURCES IN THE MEITERRANEAN SEA Problems of Shared and Straddling species: 2-Proposed action to overcome these problems: Issuing of limited licenses to fish closed fishery zones and/or seasons, (including marine parks or reserves). The collection of license fees for use of the resources, and realistic penalties for misuse of the resources Strict monitoring and control of the disposal of organic waste and nutrients into the shallow shelf-sea environment Promotion of studies aimed at improving fishing gear, gear selectivity The establishment of a code of conduct for responsible fishing with regular consultation between the industry and government.
3- SPECIAL PROBLEMS IN FISHERY RESOURCES IN THE MEITERRANEAN SEA Discarding: Wastage fish= (discarded fish ) 1- Reasons : Target species may be discarded because they are too small or below minimum landing size (MLS)or damaged upon capture and also will either not be acceptable to the market or will command an uneconomic price. Target species which are acceptable to the market and legal may still be discarded in favour of better sized or quality individuals. Marketable non-target species which have a lower value than the target species may be discarded to reduce the workload on the crew or to preserve storage capacity required for higher priced target species. Non-target species will be discarded if there is no financial return to be generated once they are landed e.g. starfish have no commercial market value. At the beginning of a lengthy trip discards may occur of species which do not keep well, such as shark.
3- SPECIAL PROBLEMS IN FISHERY RESOURCES IN THE MEITERRANEAN SEA Discarding: 2- Proposed actions to reduce it: International, regional and national agencies have adopted a number of measures to prevent discarding: Minimum landing size (MLS) below which fish may not be landed for sale. Technical measures like regulation of mesh size in areas with high discards. Closed areas to reduce discards by restricting fishing in areas where catches of juvenile fish may be high. Identification of critical areas such as nursery zones where discarding of juveniles occurs.
4- Potentials and Constraints for Sustainable Mediterranean Fisheries Development: The development of the Mediterranean has a number of dramatic changes in its ecological bodies that are attributable not only effects of fishing, but also, and perhaps independently, to the effects of the discharge of organic wastes from human activities, toxic or nitrifying or otherwise into its marine environment. Two types of effects occur due to the human activities in Mediterranean Sea: 1- Top-down effects: This due to the removal or reduction of apical predators (notably seals and small cetaceans and in the numbers of large predatory fish such as bluefin tuna). This can lead to increase abundance of prey species of fish and other organisms with low economic values.
4- Potentials and Constraints for Sustainable Mediterranean Fisheries Development: 2- Bottom-up effects: These are due to Increased discharges of organic materials and nutrients which lead to increased phytoplankton blooms of species different from those found in un-enriched waters. These blooms can affect marine vegetation by reducing light penetration, and in decomposition, lead to seasonal and eventually permanent anoxia of bottom and shelf waters. and can cause a decline in benthos, crustacean and molluscan shellfish, and in the demersal fish. In the pelagic food web, zooplankton species often a typical of the un- enriched environment, increase in abundance. Initially, they support growth of populations of small pelagic fish, but also of other pelagic predators of no commercial value such as medusae (jellyfish and ctenophores).
5 Proposed actions to achieve sustainable Mediterranean Fisheries: Exploitation of the unexploited mesopelagic resources which include mesopelagic fish, small crustaceans and cephalopods. Reducing the large proportions of edible by-catch that lost in fishery operations. limited licensing of vessels. Coastal Mediterranean States should cooperate through meetings of a regional management body attended by involving decision-makers representing those States. strict control of discharge of toxic wastes, nutrients, silt and soil run-offs and airborne pollution entering the sea. adjacent countries fishing a common stock, should co-operate to harmonize their management regimes. preparing common data bases on the environment, resources and socio- economic activities within and around the Mediterranean Sea countries. finding solutions to the problems of transit through straits and estuaries of migratory fish species.
5 Proposed actions to achieve sustainable Egyptian Mediterranean Fisheries : Assessment of the impact of the currently used fishing gear on stock of fish and implementation of new gear with appropriate mesh size. Complete prevention of the beach seine. Management of fishing effort according to the type of gears to obtain the maximum sustainable yield through: Limitation of number and size of fishing vessels. Prevention of fishing with all fishing gears during the period from April-May (spawning season of most fish species). Legislation of fishing gear and fishing activity. Developing long-range fisheries of Egyptian marine waters by joint venture agreements with Arabian and African countries to absorb excess fishing effort. Supporting financial structure of Egyptian fishery cooperative and union of fishermen and offering subsides and other forms of incentives to fishermen in closed season or areas and improving their living settlements.
6. Stock Assessment methods applying for Mediterranean Fisheries : Acoustic Technique Fishing Surveys Tagging Techniques Eggs and Larval surveys Stomach content analysis Catch and Effort statistics
6. Stock Assessment methods applying for Mediterranean Fisheries : Acoustic Technique: Advantages: -Can be used to assess exploitable stocks which have not yet been fished. -Provide the capability to survey a resource rapidly. -Recommended to be used with pelagic stocks Disadvantages: -Do not provide species composition or other biological information -Not suitable for most demersal stocks -Has high costs -Need well trained people
6. Stock Assessment methods applying for Mediterranean Fisheries : Fishing surveys: Advantages: - provide species composition or other biological information needed -Can be used to assess exploitable stocks which have not yet been fished. -Provide the capability to survey a resource but not rapidly. -Recommended to be used with demersal stocks Disadvantages: -Need similar fishing vessels working with the same fishing gears at the same time. -Has high costs