Expanding the conceptual framework of the spatial population structure and life history of jack mackerel in the eastern South Pacific: an oceanic seamount region as potential spawning/nursery habitat

Abstract

Juvenile jack mackerel were found in 2009 in the Challenger break and the East Pacific ridge (CHAEPR). This seamount region is ∼3500 km from the coastal historic jack mackerel nursery grounds off Chile (north of 30°S). We reviewed historic evidence of juveniles around this seamount and data on several local environmental conditions: sea surface temperature, chlorophyll-a, wind, turbulence levels, and Eddy kinetic energy (EKE). A Lagrangian model for the early life stages of jack mackerel in the eastern South Pacific was used to assess the potential of the seamount region as a permanent nursery ground. Transport/retention mechanisms were assessed by releasing virtual particles coupled to a growth model into the flow simulated by an eddy-resolving ocean model. Model simulations showed high inter-annual variability for particle retention in the seamount region; high retention levels were associated with low EKE such that the particles were retained for several months. Satellite altimetry has shown a local minimum in eddy activity in the region where the juveniles were observed; this minimum was consistent with the above temporal relationship. The inclusion of the CHAEPR oceanic seamount region as a potential nursery ground for jack mackerel expands the current conceptual framework for the spatial population structure of this species in the South Pacific off central Chile proposed by Arcos et al. (The jack mackerel fishery and El Niño 1997–98 effects off Chile. Progress in Oceanography 49: 597–617, 2001). Finally, we discuss the relevance of seamounts playing a double role (spawning and nursery grounds) from the standpoint of conservation and biodiversity.

Quantification and Distribution of Omega-3 Fatty Acids in South Pacific Fish and Shellfish Species

“…Furthermore, the spawning season has probably also a significant influence on the difference in lipid content found in mackerel and jack mackerel. In the current work, both species were captured in winter, that is, out of their spawning season which takes place in spring and summer [17,18]. However, in our previous study, they were captured in summer.…”

Remote Sensing of Ocean Fronts in Marine Ecology and Fisheries

“…Front data were radioed daily to Dr. Nikolay A. Shurunov, a fisheries oceanographer aboard the Russian trawler Pioner Nikolayeva, which shadowed R/V Dmitriy Mendeleyev for a month, using the near-real time front data to increase fishing efficiency. The affinity of Trachurus murphyi to the Subtropical Front in the South Pacific has been confirmed in numerous studies and exploited by fishers (Ashford et al, 2011;Parada et al, 2017).…”

A first assessment of atresia in the Chilean jack mackerel <i>Trachurus murphyi</i> (Teleostei, Carangidae) from the South-eastern Pacific Ocean

“…murphyi have a reproductive strategy to disperse over their spawning oceanic area associated to SST warmer than 15-16 °C (Cubillos et al 2008). According to Vasquez et al (2013), the reproductive activity of T. murphyi is highly correlated with the Subtropical Convergence or Subtropical Front (STF), which separates relatively warm and salty tropical waters from colder and fresher Subantarctic waters (Vasquez et al 2013, Parada et al 2017. The results indicate that SST is an important variable explaining the presence of atresia in T. murphyi, and eventually SST higher or lower than the optimal temperature for spawning, could generate a mismatch between reproduction and optimal environmental conditions for progeny development (Miranda et al 2013).…”

“…Interestingly, otolith chemistry indicates that all adult Chilean jack mackerel come from the same oceanic spawning area (Ashford et al 2011). Recently, Parada et al (2017) indicated the presence of a potential new spawning and nursery ground area associated with the seamount region in the Challenger break and the East Pacific ridge (32°S-39°S and 105°-126°W).…”