Surprisingly, there is limited literature on the global importance of supporting the krill to baleen whale food web transfer, but 14 mention benthos, the animals that live on, in, or near the bottom of a sea, is related to phytoplankton production in the Arctic Ocean food web and phytoplankton supports production of zooplankton and krill, pelagic fish and baleen whales. However, the role of baleen whale feeding on trophic transfer from phytoplankton, to zooplankton and krill, fish and ultimately baleen whales in open ocean areas is not well known. For example, 15 found baleen whales in the Barents Sea were mostly associated with the presence of krill, and to a lesser extent with capelin, amphipods and polar cod, but they had no information on transfer of krill consumption to whales. Hence, to address the global krill to whale food web, the novel approach of using published Ecopath Model data was used to describe the krill to whale trophic transfers.

The literature indicates nutrient recycling process by whale consumption of krill and fish could occur globally. In terms of global processes, 16 studied the global importance of nutrient recycling for ecosystem production and 17 found nutrient cycling was associated with cetaceans, marine mammals including whales, dolphins, and porpoises, consumption of fish, rather than krill. The study by 18 sampling the Gulf of Maine was dominated by baleen whales and the whales sustained production where they occurred in high densities. Most of the nitrogen released by defecation was as ammonia in the shallower portion of their depth range. The recycled nutrients were expected to increase local phytoplankton production, leading to increased zooplankton, Euphausiids, and small pelagic fish consumed by the whales. That was upheld by 19 who found whales can influence food web biogeochemical cycles by moving nitrogen and iron to surface waters. Furthermore, 20 suggested implementation of global processes to maintain whale numbers could increase nutrient recycling and release fisheries from the effects of overfishing. The study by 21 found pre-whaling populations may have supported productivity in global large marine regions through enhanced nutrient recycling of iron and in regions limited by nitrogen or phosphorous. That was also noted by 22 who suggested the whale numbers could have increased production of marine ecosystems and the current population removing significant levels of carbon from the atmosphere. The literature also indicates increased water column nutrients by consumption of fish during migrations 17. They noted whale defecation in the normally nutrient limited world’s deep-water oceans is likely to increase the production of surface waters via upwelling processes, and likely due to returning to surface water to breathe where defecation introduces nutrients. Hence, this paper describes the global importance of quantifying the krill to whale component of the pelagic food web.

The global baleen whale migrations are known to occur along productive continental western coastal areas due to upwelling of nutrients on their way to breeding grounds (See migration maps in 23 and description of whale migrations in 24. Upwelling is an oceanographic process involving movement of dense, cooler, and mostly nutrient-rich water from deep water towards the ocean surface, replacing the warmer nutrient-depleted surface waters. Due to the prevalence of upwelling of nutrients to surface water production 25 it is not surprising that whale migrations tend to occur along the west coast of continents. The migration map in 26 shows baleen whale migrations from the Bering Sea Arctic along the west coast of North America to Mexico, including out to Hawaii by humpback whales, and blue whales migrating further south to Costa Rica. In addition, blue whales, including humpback whales, are shown to migrate up the west coast of South America to southern Ecuador 27, which are likely originating from the Southern Ocean via the Antarctic Peninsula. The benefit of upwelling to whales is also supported by 28 who showed high Euphausiid densities of Thysanoessa spinifera and Euphausia pacifica are supported by high primary production on the west coast of North America in Monterey Bay, California and potentially by blue whale feeding on the krill.

In the southern hemisphere, migration was noted In Western Australia and the east coast of Australia and islands of the South Pacific (Oceania). A source of whales at islands of the South Pacific was indicated in the Ecopath Model of Bali Strait, Indonesia by 29. They noted whales migrate from the Indian Ocean to Pacific Ocean via passages between Indonesian Islands. Although they only noted Minke Whales (Balaenoptera acutorostrata and Sperm Whales (Physeter catodon) at Bali, it is likely they came from the Antarctic via Western Australia 30, likely along the archipelagos and range of islands at Ashmore, Cartier, Timor and Suva to Indonesia. However, 24, see their Table 2, reported Blue whales from Antarctica migrate to the west coast of Australia in the eastern Indian Ocean and then north into the Banda Sea, around Timor, Indonesia. They also noted Humpback and baleen whale breeding stocks off Western and Eastern Australia, southern right whales off south-central and southwestern Australia. Furthermore, the map by 26 also shows migrations in the southern Atlantic Ocean occurred in productive coastal areas of Brazil and southwestern Africa. In the Indian Ocean, migrations were noted south of the Horn of Africa in the Somali Sea, south-eastern Africa and Madagascar, and in the Pacific Ocean. In addition, they showed breeding and calving during summer and winter areas along continental western South America to the Corcovado Gulf in Chile. Those supplement the location of global humpback whale breeding and calving areas by 23. In addition, whale migrations from the Arctic to the Caribbean islands are shown by 31 and to the Azores Islands on west coast of South America by 32 in their Ecopath Model. Although the model does not show results for local krill species, it found the baleen whales consume 13.6% fish in their diet. The study by 33 reported whale migration from Antarctica to Tanzania, eastern Africa on the coast of the Indian Ocean for breeding,

Seven Ecopath Models were found that include the Arctic and Antarctic Ocean areas, and in migration areas in the Atlantic, Pacific and Indian Oceans. The associated feedback loops of baleen whale consumption of krill production with increased phytoplankton and benthos production due to nutrient recycling were investigated. Note that a feedback loop is a process of maintaining ecosystem stability, due to the output of a process influencing the input. Benthos production was included because detritus produced by whale defecation likely increases benthos production as 34 showed benthos surface feeders consume detritus. As the published global whale migration paths also showed baleen whales tend to migrate in productive coastal areas due to upwelling, the Ecopath Model for the Northern California Current by 56 was also included to investigate the relative contribution of baleen whales to coastal production.

An additional factor was that 35 suggested the amount of krill consumed by baleen whales could be reduced by consumption by other predators such as penguins. Hence, the amount of krill production consumed by other main predators was estimated using the Diet Matrix shown in the Ecopath models, which defines the proportion of each prey in the diet of every predator in the ecosystem. As trophic transfers of prey consumption to predators involve the consumption of prey biological production rather than biomass 1, the trophic transfer method developed by 36 was used to estimate biological production transfer from krill to baleen whales as well as for other predators. Hence, it is suggested the application of various Ecopath Models across key oceanic systems and the integration of ecosystembased fishery management (EBFM) principles quantifies the influence of krill-whale interactions on nutrient recycling, phytoplankton regeneration, and benthic productivity. Importantly, the EBFM for managing fisheries maintains the marine ecosystem stability by supporting the role of predators and interactions between species in trophic levels. Accordingly, the literature was used to develop new knowledge and insights for the aim of understanding the global importance of baleen whale consumption of krill and associated sustainability of ecosystem production by feedback loops. The large marine ecosystem theory discussed by 37 was the beginning for investigating potential feedback loops. However it should be understood that 38 showed an increase in phytoplankton production in the Arctic Ocean was not due to whales but may have been due to increased new or recycled nutrients by climate change effects of reduced sea ice cover.

The Ecopath Model by 39 for the Antarctic Ocean Krill (Euphausia superba) fishery area of 3.7 million Km² was used to estimate the krill to baleen whale TTE and krill consumption. The average transfer efficiency from prey production to predator production for a given trophic level ranging from TL 1 phytoplankton to TL5 upper predators was estimated by Equation 6 from 36 by:

TTE = 0.54 x TL_pred^-1.26 (1).

In this situation, TL_pred is the trophic level of the predator, in this case baleen whales are the main predator in the Ecopath Model with krill as the dominant prey. Additionally, the biological production transfer is the essential component of the prey to predator pelagic food web, which 36 showed maintains the production of predators for ecosystem stability.

To estimate the biological production consumption of prey by a predator it is necessary to know the biological production, P, of the prey, shown by 1 from Ecopath Model results by multiplying biomass, B, by the production to biomass ratio, P/B, giving P = B x (P/B). From ecosystem food web principles, 36, see their reported Equation 4, estimated the consumption of prey biological production by a predator, Q_pred, was related to the prey biological production, P_prey, and the TTE by:

Q_pred = P_prey x √(TTE) (2).

The prey biological production consumption, Q_pred, in equation 2 is modified by applying the proportion of krill in the predator diet from the Diet Matrix in the seven Ecopath Models to the prey biological production, P_prey. Hence, the prey biological production is adjusted in equation 3 by:

Q_pred = P_prey x √(TTE) x Diet_Pred (3).

Note that Q_pred is not the total consumption of prey production by a predator because most of the food consumed, other than the approximate 10% food web transfer, is lost due to respiration and to detritus, as explained in the Ecopath Model by 1. The production transfer does not include losses, as Q_pred is the krill prey production consumed by baleen whales, in this case, during summer. Also, during migrations the literature indicates baleen whales consume a mix of krill and fish species, which was recorded at the Chatham Rise Diet Matrix, so the total consumption by whales was estimated using krill and fish diets. As the krill species vary in migration areas, the Ecopath Model takes the various biomass and P/B ratios into account for estimation of biological production.

As the number of suitable Ecopath Models was limited to seven, a comparison is shown below for possible further research on the global importance of baleen whales contributing to nutrient recycling.

The above results for feedback loops for phytoplankton and benthos production show the highest levels in the Antarctic Ocean with the highest baleen whale biomass. The relationships shown in Figure 1 provide a preliminary indication of the global importance of baleen whale biomass on increased ecosystem production via defecation and nutrient recycling.

PP (tww/Km²/y) = 3441.4 x Whale Biomass (tww/Km²) + 1282.1(4).

R^² = 0.9863, n = 7, p<0.001.

Benthos Production (tww/Km²/y) = 187.42 x Whale Biomass (tww/Km²) + 47.682(5).

R^² = 0.988, n = 7, p<0.001.

The baleen whale biomass contribution to phytoplankton and benthos production at Alaska was estimated using the above equations and gave phytoplankton production as 1862 ± 186 tww/Km²/year, about 90% of the Ecopath Model, and benthos production 77 ± 8.5 tww/Km²/year, 86%. Errors are from the overall CV error for the seven regressions in Figure 1 for phytoplankton production, which gave average 0.10, maximum 0.35 and minimum 0.01, and the seven benthos production averaged 0.11, maximum 0.45 and minimum 0.07. The comparisons show baleen whales made a significant contribution to the Alaskan coastal production, probably by their influence on nutrient regeneration, and aided production of krill with a similar production as at the Antarctic with consumption by the other predators.

However, further along the high upwelling American western continental shelf where baleen whales also tend to migrate, the Ecopath model by 55 Field et al. (2006) for the Northern California Current found the phytoplankton production 6,600 t/Km²/year, about 3-fold higher than at Alaska. That gave a higher krill production of 216 tww/Km²/year but the baleen whale biomass was about half at 0.083 tww/Km², and similar benthos production 110 tww/Km²/year. The contribution by the lower whale biomass by equations 4 and 5 show they could gave have provided 1568 (24%) and 63 tww/Km²/year (57%), to the Northern California Current production, respectively. The higher krill production is also consistent with the higher phytoplankton production, giving a similarly expected 227 tww/Km²/year krill production (Alaskan krill 69.7 x 6600/Alaskan PP 2028), indicating baleen whales contribute to upwelling driven production in coastal areas.

The actual increase on phytoplankton production in surface waters by baleen whale defecation is not well defined, particularly when feeding on fish during migrations. However, baleen whale defecation was shown by 56 to provide dissolved iron input to Antarctic surface waters, and that may apply during migration to warmer areas. The study by 57 suggested baleen whales undertake northern winter migrations after consuming large amounts of krill in the Southern Ocean during summer. That also occurs because the calves need warmer water temperatures to survive 58. During their long migrations to the temperate and tropical areas they consume small pelagic fish such as herring 59, anchovies 60 and benthopelagic species such as sand ells 31, which live and feed near the sea floor, in midwaters or near the surface, feeding on benthic as well as free swimming fish, apparently to provide additional energy and minimize weight loss. In terms of global migrations, and 61 suggested the Southern Ocean has an important role in the global ocean biogeochemistry for the chemical, physical, geological, and biological processes of the natural environment, as well as primary production by supplying nutrients to the global gravitational circulation and currents, caused by a sinking mass of dense sea water that moves toward the ocean floor due to gravity, winds, and the rotation of the earth.

In the Arctic Ocean, 62 showed baleen whales on the western Greenland continental shelf consume the high concentrations of krillMeganyctiphanes norvegica and Thysanoessasp. Those aggregations likely aid the start of migrations to the tropics during winter and 63 showed in the Arctic Ocean during summer, baleen whales mostly feed on Krill species or fish. In addition, 64 estimated globally, prior to the whale population being reduced by fishing, that whales contributed significant nutrient enrichment of surface waters by their high prey consumption providing increased fish production. That condition most likely applies at present because 65 estimated, post-whaling, the whale population has globally recovered by about 70%. In relation to obtaining fish food during migrations, 66 showed that by moving north from the Antarctic waters, baleen whales could also obtain food by consuming small pelagic fish by diving at productive seamount areas, which is briefly reviewed in the next section.

A detailed report on seamounts was presented in 67 and recent research on baleen whale migrations has found they tend to follow seamounts associated with nutrient release from hydrothermal vents 68, which act as hot springs on the ocean floor, releasing heated, mineral-rich water into the ocean water. In the South Pacific Ocean, whale migration occurs from the Southern Ocean to the large area of seamounts shown by 69 around New Zealand, mostly on the eastern side of the islands, where most whales are reported. The whales were probably following seamounts associate with the Southern Pacific Antarctic Ridge hydraulic vents, north of the Southern Ocean 70, see their Figure 1, and then along the east Coast of New Zealand via the Macquarie Ridge to the Campbell Plateau . The ridge then turns west via the Norfolk Island Ridge to New Caledonia, in the South West Pacific Ocean, where seamounts also occur 71.

The association of seamounts with whale migrations is reported by 72 who showed increased production of the waters associated with seamounts was due to upwelling of nutrients by interaction with local deep sea water currents of the Antarctic Circumpolar Current, an ocean current that flows clockwise (as seen from the South Pole) from west to east around Antarctica. In addition, 73 showed oceanic conditions at deep-water hydrothermal vents could provide increased phytoplankton production by upwelling of dissolved iron from the vent plume to surface waters of the Southern Ocean. That was confirmed by 74, who found ammonia and iron in vent plumes may reach some surface waters in temperate areas.

In the Arctic Ocean, humpback whales (Megaptera novaeangliae) are shown migrating from the Norwegian Svalbard archipelago in the Barents Sea to the Caribbean Islands, via Iceland, by 75, see their Figure 1. The migration was along the mid-Atlantic Ocean ridge deep-ocean hydrological vent map shown in 70 and deviated from the ridge to the eastern extent of islands in the Caribbean Sea. The return whale migration from the West Indies tended to follow the mid-Atlantic Ridge and went close to the Azore islands off the west coat of Africa, then rejoined the original migration path at Iceland. The comparison is consistent with seamounts associated with the mid-ocean ridges as important for pelagic fish and their predators 76, 77, 78 and 79.