A Taxonomic Survey of Female Oviducal Glands in Chondrichthyes: A Comparative Overview of Microanatomy in the Two Reproductive Modes

Oviducal glands (OGs) are distinct expanded regions of the anterior portion of the oviduct, commonly found in chondrichthyans, which play a key role in the production of the egg in-vestments and in the female sperm storage (FSS). The FSS phenomenon has implications for understanding the reproductive ecology and management of exploited populations, but little information is available on its taxonomic extent. For the first time, mature OGs from three lecithotrophic oviparous and four yolk-sac viviparous species, all considered at risk from the fishing impacts in the central western Mediterranean Sea, were examined using light microscopy. The OG microanatomy, whose morphology is generally conserved in all species, shows differences within the two reproductive modalities. Oviparous species show a more developed baffle zone in respect to viviparous ones because of the production of different egg envelopes produced. Among oviparous species, Raja polystigma and Chimaera monstrosa show presence of sperm, but not sperm storage as observed, instead, in Galeus melastomus and in all the viviparous sharks, which preserve sperm inside of specialized structures in the terminal zone.

Contributions to Management Strategies in the NE Atlantic Regarding the Life History and Population Structure of a Key Deep-Sea Fish (Mora moro)

With the commercial fishery expansion to deeper waters, some vulnerable deep-sea species have been increasingly captured. To reduce the fishing impacts on these species, exploitation and management must be based on detailed and precise information about their biology. The common mora Mora moro has become the main deep-sea species caught by longliners in the Northeast Atlantic at depths between 600 and 1200 m. In the Azores, landings have more than doubled from the early 2000s to recent years. Despite its growing importance, its life history and population structure are poorly understood, and the current stock status has not been assessed. To better determine its distribution, biology, and long-term changes in abundance and size composition, this study analyzed a fishery-dependent and survey time series from the Azores. M. moro was found on mud and rock bottoms at depths below 300 m. A larger–deeper trend was observed, and females were larger and more abundant than males. The reproductive season took place from August to February. Abundance indices and mean sizes in the catch were marked by changes in fishing fleet operational behavior. M. moro is considered vulnerable to overfishing because it exhibits a long life span, a large size, slow growth, and a low natural mortality.

Human impacts

Coastal soft sediments are closely linked to human activity both on the land and at sea and consequently they are subjected to a wide array of human impacts. Looking for some general patterns in the consequences of impacts, this chapter identifies a range of different ecological changes as a result of direct impacts and then moves to address indirect effects. The chapter looks at the connections between local and global impacts focussing on eutrophication, fishing impacts, sediment run-off from land and plastic pollution. This leads to an introduction into the challenges of addressing multiple stressor effects, cumulative effects and the stress and disturbance-induced homogenisation of seafloor habitats and communities. The history of impact in coastal ecosystems often means that we have no appreciation for what has been lost in terms of biodiversity and ecosystem function. The chapter emphasises that to address the challenges of human-induced changes in soft sediments, we need good knowledge of how seafloor ecosystems function and how ecological systems as a network of interactions respond to change.