Notes on two rare species of brachyuran crabs (families Matutidae and Parthenopidae) from Indonesian waters with new distribution records

This research aimed to report two species of Brachyuran crabs that were found rarely from Indonesian waters. The latest report was more than one hundred years ago, and the study from Indonesia before was not so clear, both information about specimens and location details. We conducted our study in Southern Aru Island and Malacca Strait using trawl during the cruise research which was held by the Research Institute for Marine Fisheries, Ministry of Marine Affairs and Fisheries. Our findings were Izanami reticulata, New Record (family Matutidae) from Southern Aru Island, and Cryptopodia fornicata (family Parthenopidae) from Malacca Strait. The two locations are located close to the location where the species was found in previous studies, namely the Arafura Sea which is adjacent to the Aru Islands, and the Malacca Strait which is adjacent to Borneo. We suspect that the presence of these two species in western and eastern Indonesia was due to their distribution during the pelagic larval stage through the sea current. This article also provided the specific habitat for both species which has not been stated. In addition, this article will contribute to strengthening Indonesia as a mega biodiversity country with initiate compiling the database of Brachyura in Indonesian waters.

Strategies for Successful Scallops Spat Collection on Artificial Collectors in the Taranto Gulf (Mediterranean Sea)

The high variability in natural recruitment of Pectinidae is a common feature of many marine invertebrates with a pelagic larval stage, but may negatively affect aquaculture activities. Detailed information on settlement patterns and spat availability is required to reduce costs and labor. In this regard, we attempted to establish the precise immersion time and the deployment dates for spat collectors in the Taranto Gulf (Mediterranean Sea, Italy). The first experiment was carried out from June to October 2013, deploying collectors every 15 days and retrieving them after 4, 6, 8, and 10 weeks. Results from the first experiment allowed us to select 8 weeks as the best immersion time for spat collection. The second experiment was carried out from June 2013 to July 2014 when we deployed spat collectors every 15 days and recovered them after 8 weeks to detect the favorable periods to place the collectors in water to obtain the highest scallop spat harvest rate. Mimachlamys varia was the most abundant pectinid (greater than 90%), whose recruits were collected during most of the year studied, followed by Flexopecten glaber with the highest rates in July (87%) and Pecten jacobaeus, which never exceeded 17% of collected spat. M. varia had a long recruitment period (from October to early June), F. glaber showed a high number of spat during autumn months and from June to July while P. jacobaeus showed a restricted period of spawning. Our experiments provide useful insights into strategies for establishing scallop aquaculture in order to promote these mollusks as alternative candidates for aquaculture farming in the area.

Sexual differentiation in juvenile American lobster (Homarus americanus)

American lobsters (Homarus americanus H. Milne Edwards, 1837) settling to the bottom after their pelagic larval stage are sexually undifferentiated. Based on stereomicroscope observations, the female’s gonopore first appeared for lobsters about 13 mm carapace length (CL) and the dimorphism of the first pair of male pleopods was first observed at about 15 mm CL. Based on histological observations, the internal reproductive system for both males and females began differentiating at sizes ≥20 mm CL. The vasa deferentia were observed for males >30 mm CL indicating that the male reproductive system is fully formed. For females, the ovaries were observed at sizes ≥20 mm CL, but the oviducts were not detected in animals <36 mm CL. The male reproductive system is morphologically complete at a substantially smaller CL than for females.

Total stock size and cannibalism regulate recruitment in cod (Gadus morhua) on the Faroe Plateau

Steingrund, P., Mouritsen, R., Reinert, J., Gaard, E., and Hátún, H. 2010. Total stock size and cannibalism regulate recruitment in cod (Gadus morhua) on the Faroe Plateau. – ICES Journal of Marine Science, 67: 111–124. Year-class strength of fish is often considered to be determined at the pelagic larval stage, but we show that year-class strength of cod on the Faroe Plateau seems to be determined later, at the 1- or 2-group stage. Adult cod (C), measured in terms of the catch per unit effort (cpue) of small longliners, move into nearshore nursery areas of juvenile cod when in poor condition and probably displace 1-year-old cod to deeper water, where they are cannibalized. In addition, the recruitment of 2-year-old cod, at least up to a certain level, is positively related to the total biomass (B) of older cod on the Faroe Plateau, which are present at about the same time as the recruitment event. This feature, which seems to be a new observation in terms of the recruitment dynamics of cod, is possibly related to enhanced foraging or a reduced predation risk. The recruitment of 2-year-old cod during the years 1984–2006 is described by aB/C + d (r2 = 0.87), where a and d are fitted constants. The implications for stock assessment and management are discussed.