Aleksandar Joksimović

Additional record of Fistularia commersonii from the Adriatic Sea (Montenegrin coast)

An additional record of one of the most successful lessepsian migrants in the Mediterranean, Fistularia commersonii (Osteichthyes: Fistularidae), indicates the spreading of this species in the Adriatic Sea. This is by far the only lessepsian migrant with multiple confirmed records, separated in time and space, for the Adriatic. Its fast spreading is followed by rapid population explosion at invaded areas and potential effects on the local fish fauna are emphasized.

Distribution and abundance of eggs and estimation of spawning stock biomass of anchovy, Engraulis encrasicolus (Linnaeus, 1758), in the south-eastern Adriatic Sea

Seasonal distribution and abundance of anchovy eggs were analysed during three scientific cruises carried out from summer 2006 to summer 2007 in the Boka Kotorska Bay, and one cruise in July 2008 in the open waters of the south-eastern Adriatic Sea. Daily egg production method (DEPM) was applied for the first time for estimation of the anchovy spawning stock biomass in the south-eastern Adriatic Sea. The daily egg production was 13–581 eggs day −1 within the bay, and 42–110 eggs day −1 in the open waters. Anchovy egg abundance was highest in spring inside the Bay of Kotor (one of the innermost and eutrophic sub-bays of the Boka Kotorska Bay), which indicates that the conditions for anchovy spawning are very favourable in this part of the Adriatic Sea, even when temperatures are below the optimum. This study has shown that the Boka Kotorska Bay is an area of very intensive spawning of anchovy, and that small-size anchovies live and spawn in the bay, and after spawning migrate towards open waters. The length at which 50% of anchovy were mature (L50) was calculated as 9.28 for females and 9.02 for males. Spawning stock biomass was at a stable level during the period of investigation.

A holistic approach to the age validation of Mullus barbatus L., 1758 in the Southern Adriatic Sea (Central Mediterranean)

The growth of Mullus barbatus has been widely studied using different methods, but no previous study has focused on age validation. The uncertainty in estimating the age of the red mullet by otolith reading is linked to the number of false-growth increments laid down before the annulus. The capture of red mullets in the early life stage allowed us to estimate their size at the metamorphosis from the pelagic to the demersal phase. The comparison between the metamorphosis size and the back-calculated length of the first growth increment clarified the position of the false growth increment on the otolith. Moreover, the analyses of the otolith marginal increments in adult and juvenile specimens allowed us to define the deposition patterns of their annuli. The modal components of the length–frequency distribution analysis (LFDA) were identified in the winter survey (ELEFAN and Bhattacharya methods), and they did not show significant differences from the length back-calculation of the annuli. Moreover, no significant differences were found between the growth curves calculated by otolith reading (back-calculation and direct otolith reading) and the LFDA. The agreement between the length–frequency results and the otolith age estimation either corroborated or indirectly validated the growth pattern estimated in the otoliths of the red mullet, mainly when the direct validation methods (e.g. mark-recapture, captivity, radiochemical) were difficult to implement, like the case of this species. The comparison of the results of the present work to previous Mediterranean studies showed agreement with the slow growth pattern.

Detecting the occurrence of indigenous and non-indigenous megafauna through fishermen knowledge: A complementary tool to coastal and port surveys

Marine bioinvasions and other rapid biodiversity changes require today integrating existing monitoring tools with other complementary detection strategies to provide a more efficient management. Here we explored the efficacy of fishermen observations and traditional port surveys to effectively track the occurrence of both indigenous and non-indigenous megafauna in the Adriatic Sea. This consisted mainly of mobile taxa such as fishes, crustaceans and molluscs. Port surveys using traps and nets within 10 major Adriatic harbours, were compared with the information obtained from 153 interviews with local fishermen. Information gathered by traps and nets varied significantly and generally resulted of limited efficacy in exotic species detection. Interviews allowed tracking the occurrence of new species through time and space, providing complementary knowledge at the low cost. This combined approach improves our capability of being informed on the arrival of species of different origin, providing a more rational, improved basis for environmental management and decision making.

Composition and Distribution of Ichthyoplankton in the Boka Kotorska Bay

This paper provides an overview of all the data available on qualitative composition and distribution of ichthyoplankton in the area of the Boka Kotorska Bay. Although the research activities were not conducted continuously, the results showed a high level of diversity and abundance of certain species and proved that the Boka Kotorska Bay is one of the most important spawning areas and feeding grounds for juveniles of a number of pelagic fish species. Analysis of the plankton material resulted in identification of spawning of 40 different species from 7 genera and 20 families. Ichthyoplankton communities’ diversity was analysed by two diversity indices: Shannon’s diversity index (H′) and Simpson’s index (D). Early developmental stages of fish are one of the most sensitive phases in the fish lifecycle, so ichthyoplankton research is one of the main tasks of fisheries biology.

Cetaceans in the Boka Kotorska Bay

The Boka Kotorska Bay, as a unique geographical area, with specific ecological conditions, was always inhabited by cetaceans. There is very little recorded data on their presence in the bay. This article presents an overview of cetacean species inhabiting the southern Adriatic Sea, with a particular focus on bottlenose dolphin and fin whale, species whose presence has been documented in the Boka Kotorska Bay. A detailed review on the presence of one of the most famous dolphins in the bay, the dolphin Joca, who was a favourite with swimmers and bathers and was awarded a special protection status by the local government of the city of Kotor has been carried out. A history of unfortunate events – accidental and intentional dolphin deaths in the last 20 years – is provided, as recorded by the society for protection of animals ‘Fifi’ from Kotor. This society of volunteers was involved in the protection of the Boka Kotorska Bay environment since its founding in 1997, and the protection of marine mammals was among its activities. An overview of the first survey of marine mammal populations in the Boka Kotorska Bay area within the frame of the EU IPA NETCET project is also provided. The results of the survey represent the first scientifically collected data on cetaceans in the area. Preservation of these species in the area of the bay requires constant involvement, education of the local population and children on the importance of preservation of cetaceans and careful development of all forms of tourism, including the nautical tourism, which is one of the gravest threats to marine mammals in the Boka Kotorska Bay area.

Occurrence and Distribution of Crustacean Decapoda in Boka Kotorska Bay

An annotated species of crustacean Decapoda list is provided for the area of Boka Kotorska Bay, based on the available literature. Review of the relevant literature showed that the number of the species known in this area is 62. Two of these species are recognized as Atlanto-tropical immigrants. All species were collected using trawl, dredge, grab bottom sampler, gillnets, as well as scuba-diving techniques. Description of each species gives the valid scientific name and vernacular, common names, literature, distribution and findings in Boka Kotorska Bay, Adriatic distribution, and some remarks as well as their potential commercial interest for fishery. Most of these species have a wide distribution range, including the whole Mediterranean Sea.

The History of Fishery in Boka Kotorska Bay and Traditional Types of Fishery

Among oldest occupations that the local population in the Boka Kotorska Bay has been engaged in, since the ancient times, is sea fishing, but despite the fact that it has centuries’ old tradition in this region, there are very few written records on the history and tradition of fishery in the Boka Bay. This paper provides an overview of the basic fishery types in the Bay over the past centuries, describes the boats and fishing gears used in those times, but also today, as well as the manner of use of certain fishing gear types. It gives also an overview of historical development and changes in some fishing gears over the time as well as changes in socio-economic and social relations in fishery. Apart from its economic significance, the fishing with traditional gear in the Boka Kotorska Bay also has a strong culturological and sociological importance for the local population and as such, it should be preserved and protected at the times of industrialization and development of the coastal area. Activities aimed to preserve the traditional fishery types in the Boka Kotorska Bay should also be implemented in order to diversify further the tourist offer of Montenegro since, in addition to provision of fresh, wholesome food from the sea the use of traditional gear is also a tourist attraction.

Bioindication of aquatic ecosystems on the base of the assessment of functional state of freshwater bivalve mollusks

The paper is devoted to approbation in laboratory and field conditions of a new method of bio - indication of aquatic ecosystem state on the basis of assessment of functional state of freshwater bivalve mollusks by monitoring of their cardiac activity.

Some Aspects of the Reproductive Biology of the Deep-Water Pink Shrimp Parapenaeus Longirostris (Lucas, 1846) (Decapoda, Penaeidae) on the Montenegrin Shelf

Some aspects of the reproductive biology of females of the deep-water pink shrimp, Parapenaeus longirostris (Lucas, 1846) from the Montenegrin shelf (southern Adriatic Sea) were investigated. Sampling was performed on a monthly basis from November 2006 to October 2007. A total of 13 trawl hauls covered a depth range of 40 to 250 m. An estimate of the gonadosomatic index (GSI) showed permanent reproductive activity all year round with two maxima, one in late spring and the other in autumn. The minimum reproductive activity occurred in June. Females outnumbered males in shallow waters, while at greater depths (> 100 m) the proportion of the sexes was almost equal; the overall sex ratio was 0.7 females : males. The size at which 50% of the female population reached maturity was at a carapace length (CL) of 21.9 mm, and the smallest mature female in the samples had a carapace length of 16 mm.