You appear to have lost track of the original point regarding Stanley Park. The original point was that the total area occupied by farms was about the size of Stanley Park: every farm could fit into an area that size and a comparison of that area to the total area of coastal BC waters is therefore representative of what proportion of the total sea bottom on the BC coast is under farms.
No, I have not lost track. You said that all 100 farms would cover an area the size of Stanley Park, and I said that these 9 farms alone appear to cover a signifcant portion of Stanley Park (cover the image with clear plastic and shade the farms in with a fine tip felt pen (just the cages if you like), and then place the shaded area over the image of Stanley Park (which is already slightly larger than it should be) and you can see that these 9 farms cover about 1/3 of the park. I am no mathematician, but 100 farms would appear to cover 10 times more than 9. Now, even if you do not accept that the area directly affected by the nutrient loading is larger than the surface area of the farms, (therefore, the area affected by these 9 farms is already larger than the area of Stanley Park), you can see that the farms already cover a larger area than Stanley Park. Furthermore, I have said that comparing the area to the farms to the total area of the coast is also not as useful as comparing the size of the farms to the amount of sea floor in the immediate area (the farms around Senora Island cover an area 1/3 the size of Stanley Park).
You have yet to demonstrate the nature of any harm that might arise from any deposition that does occur or, more critically, even that harm occurs.
Sorry, I thought I had.
"Previous studies have demonstrated that the most evident consequences of fish farming on the benthic environment are an increase in total organic carbon (C) accumulation in the sediment and a decrease in oxygen availability for the benthos beneath fish cages (Holmer 1991, Holmer and Kristensen 1992, Karakassis et al. 1998). These changes, in turn, have significant impact on the abundance and biodiversity of micro-, meio- and macrobenthic organisms (Karakassis et al. 2000, Mirto et al. 2002, La Rosa et al. 2004). Other recent studies have demonstrated that fish-farming effluents have effects also on the biochemical composition of the organic matter of sediment. Fishfarm sediments are sometimes enriched in lipid content due to the accumulation of uneaten fish-food pellets on the seafloor (Mirto et al. 2002, Bongiorni et al. 2005), and are characterized by increased microbenthic algal biomass in response to the increased availability of nutrients below the cages (La Rosa et al. 2001)." (Pusceddu et al, "EFFECTS OF INTENSIVE MARICULTURE ON SEDIMENT BIOCHEMISTRY,"
Ecological Applications, 17(5), 2007, p. 1367)
In their study in the Mediterranean, Pusceddu et al. also found that "intensive aquaculture can significantly contribute to benthic eutrophication processes, although the extent of the spatial effects of fish-farm effluent is potentially limited. However, even though spatially limited, the impact of the biodeposition derived from fish farms is site specific and can be driven by both physico-chemical and trophic contexts. We have also been able to empirically derive the minimum distance at which the siting of new fish farms should be permitted in the presence of benthic systems traditionally considered vulnerable. To date, since background ecological features on a local scale appear to have the major role in affecting the patterns of fish-farm-induced eutrophication, the future siting of fish farms should include well-designed a priori monitoring programs that are able to describe the whole ecological setting and should be tailored to the basis of the local ecological context." (Pusceddu et al, p. 1376)
While they agree with you that current velocity has an effect of lowering the "fish-farm-induced benthic eutrophication" but, they also recognize in turn, that "the spatial extent of the potential impact will be spread farther from the cages than in those sites with lower bottom currents." (Pusceddu et al, p. 1372).
Closer to home:
"Waste from finfish netpens and cages flows directly into marine waters and, in contrast to terrestrial farms, there is usually no attempt to capture it. Nutrients and suspended solids discharged by salmon farms can have considerable effects on a local scale (Goldburg et al. 2001), although salmon farms sited in well flushed areas often have minimal impact on the quality of surrounding waters (Brooks and Mahnken 2003). Dilution of nutrients means that widely spaced marine fish farms sited in areas with strong currents will probably have little impact, an argument for moving marine aquaculture out of coastal waters and into the open ocean (Marine Research Specialists 2003). . . Producing a kilogram of salmon releases approximately 0.02 to 0.03 kg of N [the nutrient primarily responsible for eutrophication in marine waters], excluding losses from uneaten feed (Brooks and Mahnken 2003). About 70 000 mt of salmon were produced in British Columbia in 2003 (C Matthews pers comm) with a gross domestic product value of C$91 million, or approximately US$66 million (Marshall 2003). Thus the BC salmon farming industry discharged about 1435 mt to 2100 mt of nitrogen" or the equivalent of 200 000 hogs. (Goldburg and Naylor, "Future seascapes, fishing, and fish farming,"
Front Ecol Environ 2005; 3(1): 21–28
You may argue that the eutrophication of the seafloor beneath the farms is "insignificant" compared to the total size of the coastal sea floor, or that this harmful effect is minimized under the farms by site flushing; however, I think "the nature of any harm that might arise from any deposition that does occur" has been demonstrated.
Author
Topic: Another day another virus scare. (Read 26812 times)