Nevertheless, a lower contrast in skeletal structures was observed in the high intensity fish, in particular at the 15 g sampling, indicative of a lower mineralization rate at this stage.
Even at relatively low fishing intensities, artisanal fishing has been shown to strongly reduce populations and biomass of targeted species on coral reefs in the Indo-Pacific [52] [54], eastern Pacific [55], and the Caribbean [18].
Although we did not assess alternative ESSs for chum salmon maturation thresholds, the actual duration of this high-intensity fishing does not seem to have been sufficient to have prevented recovery of the maturation threshold after fishing ceased.
Various sensors, actuators, microcontroller, and microprocessor were employed in the system to monitor and control water quality, light intensity, and fish feed.
The potential improvement in precision when a strong relationship exists between backscatter intensity and fish density offers motivation to continue to refine relationships between underlying fish density, acoustic backscatter, and trawl catches.
General estimates of the heritability of life-history traits are low as are estimated selection intensities although fishing mortality can be very high [13], [14].
Table 2 The prevalence and mean intensity of Contracaecum larvae relative to fish species Fish species No. of examined fish No. of infected fish Prevalence % No. parasite in each fish Mean intensity O. niloticus 73266 35.6 15 50 0.6 1.9 T. galilaea 712 1 0.14 4 4 H. forskhalii 35 29 82 150–300 5.1–10.3 L. niloticus 85 85 100 15–350 0.17–4.12.
The worm burden, prevalence and mean intensities per infected fish varied among different fishes (Table 2), with 100% prevalence in L. niloticus and the highest intensity in H. forskahlii.
In some cases, the magnitude of change appears to be positively correlated with the intensity of fishing, such that life-history modification has been hypothesized to reflect evolutionary responses to intensive, size-selective fishing (Devine et al. 2012; Audzijonyte et al. 2013).
Beyond the direct (and illegal) pursuit of the giant catfish, the larger reason for their decline is probably the intensity of fishing in the Mekong over all.
