Editing Carrying capacity (section)

==Fisheries==
[[File:Sunset Fishery, Cochin, Kerala, India.jpg|thumb|A fishery at sunset in Cochin, Kerala, [[India]]]]
{{Main|Population dynamics of fisheries}}
In [[fisheries]], carrying capacity is used in the formulae to calculate [[Sustainable yield in fisheries|sustainable yields]] for [[fisheries management]].<ref>{{cite journal |last1=Quinn |first1=Terrance J. |title=Ruminations on the development and future of population dynamics models in fisheries |journal=Natural Resource Modeling |date=28 June 2008 |volume=16 |issue=4 |pages=341–392 |doi=10.1111/j.1939-7445.2003.tb00119.x |s2cid=153420994 |doi-access=free }}</ref> The [[maximum sustainable yield]] (MSY) is defined as "the highest average catch that can be continuously taken from an exploited population (=stock) under average environmental conditions". MSY was originally calculated as half of the carrying capacity, but has been refined over the years,<ref>{{Cite book|last1=Tsikliras|first1=Athanassios C.|title=Encyclopedia of Ecology|last2=Froese|first2=Rainer|publisher=Elsevier|year=2019|doi=10.1016/B978-0-12-409548-9.10601-3|pages=108–115|chapter=Maximum Sustainable Yield|isbn=9780444641304|s2cid=150025979|edition=2nd}}</ref> now being seen as roughly 30% of the population, depending on the species or population.<ref>{{cite journal | last1 = Bousquet | first1 = N. | last2 = Duchesne | first2 = T. | last3 = Rivest | first3 = L.-P. | year = 2008 | title = Redefining the maximum sustainable yield for the Schaefer population model including multiplicative environmental noise | url = http://mat.ulaval.ca/pages/duchesne/BDR.pdf | journal = Journal of Theoretical Biology | volume = 254 | issue = 1 | pages = 65–75 | doi = 10.1016/j.jtbi.2008.04.025 | pmid = 18571675 | bibcode = 2008JThBi.254...65B }}{{Dead link|date=November 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref name ="Thorpe">{{cite journal | last1 = Thorpe | first1 = R.B. | last2 = LeQuesne | first2 = W.J.F. | last3 = Luxford | first3 = F. | last4 = Collie | first4 = J.S. | last5 = Jennings | first5 = S. | year = 2015 | title = Evaluation and management implications of uncertainty in a multispecies size-structured model of population and community responses to fishing | journal = Methods in Ecology and Evolution | volume = 6 | issue = 1| pages = 49–58 | doi = 10.1111/2041-210X.12292 | pmid = 25866615 | pmc = 4390044 | bibcode = 2015MEcEv...6...49T }}</ref> Because the population of a species which is brought below its carrying capacity due to fishing will find itself in the exponential phase of growth, as seen in the Verhulst model, the harvesting of an amount of fish at or below MSY is a surplus yield which can be sustainably harvested without reducing population size at equilibrium, keeping the population at its maximum [[Recruitment (biology)|recruitment]]. However, annual fishing can be seen as a modification of ''r'' in the equation -i.e. the environment has been modified, which means that the population size at equilibrium with annual fishing is slightly below what ''K'' would be without it.

Note that mathematically and in practical terms, MSY is problematic. If mistakes are made and even a tiny amount of fish are harvested each year above the MSY, populations dynamics imply that the total population will eventually decrease to zero. The actual carrying capacity of the environment may fluctuate in the real world, which means that practically, MSY may actually vary from year to year<ref name="Milner-Gulland and Mace 1998">Milner-Gulland, E.J., Mace, R. (1998), [https://books.google.com/books?id=SfozQRjheekC&q=%22Conservation+of+biological+resources%22 ''Conservation of biological resources''] Wiley-Blackwell. {{ISBN|978-0-86542-738-9}}</ref><ref name="Larkin">{{cite journal |last1=Larkin |first1=P. A. |title=An epitaph for the concept of maximum sustained yield |journal=Transactions of the American Fisheries Society |volume=106 |issue=1 |year=1977 |pages=1–11 |doi=10.1577/1548-8659(1977)106<1:AEFTCO>2.0.CO;2 |bibcode=1977TrAFS.106....1L }}</ref><ref name="Botsford">{{cite journal | last1 = Botsford | first1 = L.W. | last2 = Castilla | first2 = J.C. | last3 = Peterson | first3 = C.H. | year = 1997 | title = The management of fisheries and marine ecosystems | journal = Science | volume = 277 | issue = 5325 | pages = 509–515 | doi = 10.1126/science.277.5325.509 }}</ref> (annual sustainable yields and maximum average yield attempt to take this into account).{{citation needed|date=March 2021}} Other similar concepts are [[optimum sustainable yield]] and [[maximum economic yield]]; these are both harvest rates below MSY.<ref>Clark, C.W. (1990), ''Mathematical Bioeconomics: The Optimal Management of Renewable Resources'', 2nd ed. Wiley-Interscience, New York</ref><ref>National Marine Fisheries Service (NMFS). 1996. Our Living Oceans: Report on the Status of U.S. Living Marine Resources 1995. NOAA Technical Memorandum NMFS0F/SPO-19. NMFS, Silver Springs, Md.</ref>

These calculations are used to determine [[Individual fishing quota|fishing quotas]].{{citation needed|date=March 2021}}