MANAGEMENT OF THE NERETVA RIVER ESTUARY: PAST AND FUTURE OF A RICH AND FRAGILE NATURAL HERITAGE

This paper presents highlights of the geography, history, and management of the Neretva River estuary. Current threats to the estuary\u27s valuable natural resources, including changes in its hydrologic regime, loss of native habitat, changes in biodiversity, and pollution are reviewed. Different proposals for the area\u27s development, and possible conflicts associated with their implementation, are mentioned. Aquaculture, properly practiced, can make a significant contribution to the Neretva estuary\u27s near- and longterm development

A Comparison of Traditional and Locally Novel Fishing Gear for the Exploitation of the Invasive Atlantic Blue Crab in the Eastern Adriatic Sea

The Atlantic Blue Crab Callinectes sapidus has been recognized as invasive in the Mediterranean Sea, where it now provides a significant contribution to artisanal fisheries. In this study, we compared the efficiency, selectivity, and productivity of American wire crab traps and traditional fyke nets for the capture of Blue Crabs in a study conducted from June to December 2019 in the Parila Lagoon (River Neretva Estuary, Croatia). A total of 7707 specimens were caught in 15 wire traps, comprising 6959 males and 749 females. The total catch using 50 traditional fyke traps was 1451 crabs, of which 1211 were males and 240 were females. In general, wire crab traps showed a higher capture selectivity and economic performance compared to fyke nets. The catch per unit effort (CPUE) was 102.76 kg for the American wire crab trap and 5.96 kg for the traditional fyke net. The CPUE of gravid female Blue Crabs was lower for the wire traps than the fyke nets. Herein, the utility of crab traps as selective fishing gear for the capture of Blue Crabs, and management tools for control of the reproductive and recruitment phases of the crab, are discussed, with the perspective of future exploitation of the species as a commercially valuable shellfish product in the Mediterranea

Occurrence of <i>Philometra lateolabracis</i> (Nematoda: Philometridae) in the gonads of marine perciform fishes in the Mediterranean region

Gravid females of the nematode Philometra lateolabracis (Yamaguti, 1935), a parasite of gonads of marine perciform fishes, were found in wild and cultured dusky grouper Epinephelus marginatus (Lowe) from waters near the Balear Islands (Spain, Mediterranean Sea) and Sicily (Italy, Thyrrenean Sea), and in the greater amberjack Seriola dumerili (Risso) in Croatia (south-eastern Adriatic Sea). In wild E. marginatus in Spain, the overall prevalence was 21% and the intensity of infection 1 nematode per fish. The nematodes are briefly described and illustrated. The species Sanguinofilaria jordanoi López-Neyra, 1951, described from the ovary of Epinephelus gigas Brünich from Morocco, is synonymized with P. lateolabracis. This is the first documented record of P. lateolabracis from fishes of the Mediterranean region and its finding in S. dumerili represents a new host record. The possible importance of this pathogenic parasite for cultures of marine perciform fishes in the region is stressed

Autohtoni nasadi mekušaca: strategijsko upravljanje, zaštita, obnavljanje i eksploatacija

It is no secret that commercially important oyster beds are declining or fluctuating sharply all over the world. In Chesapeake Bay (USA) from 1985-1990 there was a sharp decline in production from 700,000 - 800,000 kg to 4,000 - 5,000 kg. In Australia production has declined since World War II to 45% of earlier levels. The same has occurred in the Mediterranean: according to F.A.O. (1997) European oyster stocks increased from 1950-1990, but by 1995-2000 they had declined almost linearly to about one-half earlier amounts. In addition, other Molluscs are considered to represent “concave downward” declining stocks (F.A.O., 1997). The main producing countries in the East Mediterranean for the European flat oyster are Italy (46.1%), Greece (4.4%), Turkey (2.2%), and Croatia (1.5%). For other species, the main producing countries are Italy (69.0%), Greece (16.0%), Turkey (2.2%), and Croatia (3.7%). The Adriatic, with considerable river input and a high degree of eutrophication, is important for mollusc production. The main question, however, is how stable and sensitive this industry is. Starting from the main issue that the natural stocks decline the need for the elaboration of a strategic management plan for the native mollusc beds is imperative. Strategic planning is an important tool for any sector when we need to do more than react to events as they unfold. Strategic planning involves a realistic assessment of the external environment and the factors bearing on it, now and in the future. Arising from this analysis, various “strategies” can be determined which will enable overall objectives to be met. The framework of a strategic management plan includes discussion and measures on issues such as property rights, policy issues affecting water quality and quality assurance, other aspects of government administration, generic promotion and R&D. Issues affecting business structure, the specific production technology employed, brand development and related aspects of marketing, are more likely to reflect the goals of individual businesses, although there may be a role for voluntary collective action (but not mandatory, or industry-wide action) in some circumstances. Strategic planning for the development of mollusc industry is not strictly a scientific or a administration problem to solve. It is a multi-parametric and multi-sectoral problem and as in any similar case, our inability to handle multi-parametric problems results to plans with limited results or more frequently, to disasters.Općenito je poznato da su nasadi kamenica posvuda u svijetu izloženi većim oscilacijama ili su u opadanju. U SAD-u, Chesapeake Bay, u razdoblju od 1985. do 1990. zabilježeno je znatno opadanje u proizvodnji sa 700 - 800.000 kg godišnje na 4.000 - 5.000 kg godišnje. U Australiji proizvodnja je u padu od Drugog svjetskog rata, i iznosi 45%. Slično je i na Mediteranu: prema godišnjaku FAO (1997.) europski stokovi kamenica pokazivali su rast u razdoblju 1950.-1990., nakon toga opadanje je linearnog oblika pa od 1995. do 2000. iznosi 45-50%. Što se tiče proizvodnje ostalih pripadnika skupine školjkaša, smatra se da su stokovi u opadanju te prate “konkavno silazeću” putanju (FAO, 1997.). Glavni proizvođači europske plosnate kamenice na istočnom Mediteranu su: Italija (46,1%), Grčka (4,4%), Turska (2,2%) i Hrvatska (1,5%). Glavne zemlje proizvođači skupine mekušaca su: Italija (69,0%), Grčka (16,0%), Turska (2,2%) i Hrvatska (3,7%). Površina Jadranskog mora, sa značajnim dotokom slatke vode i visokim stupnjem eutrofikacije, bitno je područje za proizvodnju mekušaca. Ključno je pitanje pritom koliko je ova industrija osjetljiva i stabilna

DETECTION AND CONFIRMATION OF FRESHWATER BLENNY Salaria fluviatilis (ACTINOPTERYGII: BLENNIDAE) IN BOSNIA AND HERZEGOVINA

Salaria fluviatilis je slatkovodna vrsta ribe čiji se raspon distribucije proteže na pritoke duž Sredozemnog i Crnog mora. Smatra se ugroženom u nekoliko europskih mediteranskih zemalja. Iako je prethodno spomenuta na popisima slatkovodnih vrsta riba, njezino prisustvo zapravo nikada prije nije potvrđeno u Bosni i Hercegovini. Slijedom toga, došlo je do sumnje u njezinu distribuciju u tom području. Uzorak riječne babice dobiven je iz donjeg dijela rijeke Neretve (sliv Jadranskog mora) u Bosni i Hercegovini u svibnju 2020. godine, što predstavlja prvi pouzdan zapis o ovoj vrsti. S obzirom na to da ovaj zapis potvrđuje starija izvješća, iako ranija istraživanja nisu uspjela locirati ovu vrstu. Poznavanje sastava ribljih vrsta u riječnim slivovima i ažuriranje njihovog popisa jedan je od važnih zahtjeva za upravljanje biološkom raznolikošću svake zemlje, kao i vodenim i ribljim resursima.Distributional range of freshwater blenny Salaria fluviatilis extends to the tributaries along the Mediterranean and Black seas. It is considered endangered in several Mediterranean European countries. Although previously mentioned in the lists of freshwater fish species, its presence has never before been confirmed in Bosnia and Herzegovina. Consequently, this has led to doubts about its distribution there. A sample specimen of freshwater blenny was obtained from the lower Neretva River (Adriatic Sea watershed) in Bosnia and Herzegovina in May 2020, representing the first reliable record of this species. Considering that this record confirms older reports, however, it seems that earlier surveys have failed to locate the fish. Knowledge of the composition of fish species in river basins and updating their list are among the important requirements for managing the biodiversity of each country, as well as water and fish resources

Istraživanje europske jegulje, Anguilla anguilla u ušću rijeke Neretve (istočni Jadran, Hrvatska) korištenjem tradicionalnih ribolovnih alata

Samples of the European eel, Anguilla anguilla from two different habitats in the River Neretva estuary region were analysed using two different traditional fishery gear, in the period from 2016 to 2019. The monthly eel catches in ten traditional fyke nets in Parila lagoon varied from 4.4 to 12.7 kg (±2.45 kg) in 2016 and 2.4 to 9.6 kg (±2.01 kg) in 2019. There were no statistical differences between monthly and total weights recorded in 2016 and 2019 (t=1.04; p=0.312). The b-coefficient of the length-weight (LW) relationship for the freshwater eel samples varied from 3,1036 to 3,3206 during two-year period of the sampling. The LW relationship for the brackish population was significantly lower (b-coefficient 2,6513). The dominant eel stage in both sites was yellow eel, while silver stage was scarce. The fishery with traditional devices revealed that efficiency of these artisanal tools is low, pointing to poor abundance of eel in their common habitats. The recorded catch using bigger traditional eel trap gear during autumn spawning migrations was also dominated with yellow stage, while silver eel represented only 15,4% of the catch. The infestation of eels with the parasite, Anguillicoloides crassus was significantly higher in freshwater habitat (41% of eel specimens infested) than in brackish, Parila lagoon (7%). Poor efficiency of traditional gear, bad length and weight structure of the population and low b-coefficients of eels in their most important habitat, indicate poor status of European eel population and River Neretva estuarine ecosystems.Europska jegulja, Anguilla anguilla analizirana je u dva različita staništa u delti Neretve pomoću dva različita tradicionalna ribolovna alata za jegulju u razdoblju od 2016. do 2019. Ulov jegulje u deset tradicionalnih vrša za jegulje u laguni Parila kolebao je mjesečno od 4,4 do 12,7 kg (± 2,45 kg) u 2016. godini i od 2,4 do 9,6 kg (± 2,01 kg) u 2019. godini. Nije bilo statističke razlike između mjesečnih i ukupnih masa zabilježenih u 2016. i 2019. godini (t = 1,04; p = 0,312). b-koeficijent odnosa duljine i mase (LW) za jegulje iz slatkovodnog područja kolebao je od 3,1036 do 3,3206 tijekom dvije godine uzorkovanja. Odnos LW za jegulje iz bočatog staništa bio je značajno niži (b-koeficijent 2.6513). Dominantni stadij jegulje u oba područja bila je žuta jegulja, dok je srebrna jegulja bila rijetka. Ribolov tradicionalnim ribolovnim alatima pokazao je da je učinkovitost ovih alata niska, što ukazuje na malu brojnost jegulja u njihovim tradicionalnim staništima. Ulovom u “trati”- tradicion- alnom alatu za ulov jegulje tijekom jesenskih migracija dominirala je također žuta jegulja, sa samo 15,4% ulova srebrne jegulje. Zaraženost jegulja parazitom Anguillicoloides crassus bila je znatno veća u slatkovodnom staništu (41%), u usporedbi sa 7% jegulja iz bočate lagune Parila. Slaba ribolovna učinkovitost tradi- cionalnog ribolovnog alata, loša duljinska i masena struktura populacije i niski b-koeficijenti jegulja u najvažnijem staništu jegulje ukazuju na loš status populacije neretvanske jegulje i ekosustava ušća rijeke Neretve

Records of New Fish Species in the River Neretva Estuary: Potential Threat to Coastal Adriatic Nursery

Specimens of the three new fish species were recorded during 2015 and 2016 in the River Neretva Estuary. These species are: White trevally, Pseudocaranx dentex (Bloch and Schneider, 1801), Pilotfish, Naucrates ductor (Linnaeus, 1758) and White grouper, Epinephelus aeneus (Geoffroy Saint–Hilaire, 1817). The characteristics of caught specimens and their history of records in Adriatic Sea are described. Potential impact of new species invasion in the Neretva Estuary as a major Eastern Adriatic nursery habitat is discussed