Nephrops norvegicus in the Adriatic Sea: Connectivity modeling, essential fish habitats, and management area network

Abstract

Knowledge of connectivity among subpopulations is fundamental in the identification of the appropriate geographical scales for stock status evaluation and management, the identification of areas with greater retention rates, and space‐based fisheries management. Here, an integration of hydrodynamic, biological, and habitat models results is used to assess connectivity and support the definition of essential fish habitats (EFH) in the Adriatic Sea, with reference to Nephrops norvegicus, an important benthic commercial resource, the recruitment of which is strongly related to larval dispersal from spawning to recruitment areas. We explored oceanographic and biological connectivity in the Adriatic Sea under a wide and representative variety of oceanographic conditions (winters 2006–2012) by tracking 3D trajectories of larvae released from different areas. We used a Lagrangian model that features a specific larval behavior module with explicit dependence on environmental parameters (i.e., temperature and sediment type) and that is driven by high‐resolution hydrodynamic and meteorological data. The results were used to partition the area in which Nephrops was observed into 20 homogenous management subareas; to assess the connection between spawning, recruitment, and harvesting grounds; and to identify potential subpopulation boundaries as well as the connectivity among the potential subpopulations. The results suggest the presence of at least three distinct subpopulations, which need to be independently managed and conserved, and confirms that the Jabuka‐Pomo pit is the most important spawning area, but alone it cannot sustain Nephrops populations throughout the Adriatic Sea. The results also show the importance to move from particle‐tracking to approaches based on integrated models.

Looking for a Simple Assessment Tool for a Complex Task: Short-Term Evaluation of Changes in Fisheries Management Measures in the Pomo/Jabuka Pits Area (Central Adriatic Sea)

“…Furthermore, the presence of muddy bottoms and other exogenous factors make it an ideal habitat for Norway Lobster, Nephrops norvegicus (Linnaeus, 1758) [67]. Numerous studies reported that here the population of Norway Lobster is characterised by high densities of individuals smaller, and growing slower, than those from other areas of the Adriatic Sea [68][69][70][71][72]. Among the other crustacean species occurring in the area, a commercial and ecological relevance is attributable to the Pink Shrimp, Parapenaeus longirostris (Lucas, 1846), which in the last decade showed a relevant abundance increase in the Mediterranean Sea [73,74].…”

Long‐term interannual variability in larval dispersal and connectivity of the Norway lobster (Nephrops norvegicus) around Ireland: When supply‐side matters

“…Several studies have used biophysical larval transport models to estimate N . norvegicus larval dispersal (Marta‐Almeida et al, 2008; McGeady et al, 2021; Melaku Canu et al, 2020; O'Sullivan et al, 2015; Phelps et al, 2015). However, none have simulated larval transport on multiple mud grounds over a long time series (>10 years) to determine the extent of interannual variability in larval dispersal and population connectivity.…”

Where do recruits come from? Backward Lagrangian simulation for the deep water rose shrimps in the Central Mediterranean Sea

“…Here we focused on the deep water rose shrimp that is managed as a straddling stock, due to poor information on its spatial structure. Gaining information on the stocks structure and on the connectivity between population units is thus essential to solve the mismatch between biological and management units and identify the appropriate geographical scales for stock assessment and management (e.g., Cadrin, 2020; Fiorentino et al, 2014; Hidalgo et al, 2019; Melaku Canu et al, 2020).…”

“…The interactions of Lagrangian particles with the coastal boundary, could affect the dynamics of dispersal. In our simulations, similarly to what is generally done in larval dispersal studies (e.g., Melaku Canu et al, 2020; Palatella et al, 2014), we did not consider larval beaching/stranding on the coast but we applied reflective boundary conditions that, depending on the geometry of the domain, the run length and the strength of the velocity field, could affect the GTCs and the hotspot regions. Many models based on Lagrangian computations, analyzed the stranding effect, showing that the stranding probability of particles may be meaningful, especially in conjunction with the particle resuspension probability (see Hinata et al, 2020; Liubartseva et al, 2018; Onink et al, 2021 for applications to marine plastic debris), and the vertical migration (see Berline et al, 2013).…”

“…Unfortunately, these techniques cannot be used in crustacean species lacking of hard structures such as otoliths. Finally, further work is needed to gather more information on biological traits of species, including spawning strategy and preferential habitat (Legrand et al, 2019) and larvae biology (growth, mortality and vertical migration), in order to make connectivity models more realistic (Melaku Canu et al, 2020; Ospina‐Alvarez et al, 2012). These are all important issues for future research and will improve our understanding of the spatial structure and connectivity between subpopulations of this valuable commercial species throughout the SoS and surrounding areas.…”