Great Lakes 10-Minute Grids - Institute for Fisheries Research (IFR)

In the Great Lakes, grid systems defined by latitude and longitude minutes have been used for a number of decades as a fishery standard for data reporting. The Michigan Department of Natural Resources (MDNR) Fisheries Division created this GIS layer in 2019 to depict the MDNR Michigan Great Lakes grid (v3.2) standard for Fisheries Division applications for the waters of the State of Michigan, and for Canadian waters in the St. Clair Detroit River System (SCDRS), as of June 2019. This GIS layer was created by incorporating grid boundaries and ID values from a number of existing grid standards. This layer is a composite grid that incorporates grid boundaries and ID values from the following GIS data standards for different areas of the Great Lakes: 1) 10-minute grids for Lakes Huron, Michigan, Superior and the St. Mary’s River came from the Institute for Fisheries Research (IFR) version 1 (v1) of the 10-minute grids. 2) 10-minute grids for Lake Erie came from version 2 of the IFR 10-minute grids created by the Great Lakes GIS (GLGIS) project, and 3) 5-minute grids for SCDRS came from 5-minute grids developed by the GLGIS project. Version 1 of the IFR 10-minute grids were created in 1998, and only covered Lakes Huron, Michigan, and Superior, and the St. Mary’s River. This is the GIS dataset that was used as the grid standard for the 2000 consent decree. The grid boundaries and ID values in v1 were based off of the paper maps depicted in the 1989 Status of the Fisheries Resource Report (Technical Review Committee, 1989) with some very minor grid boundary differences likely caused by bringing the paper map into a digital GIS format. In v1, 10-minute grids do not always have rectangular boundaries where each side represents 10-minutes of latitude and longitude, especially near the shoreline. In order to create the v3.2 composite layer, some features in the v1 GIS dataset that were missing ID values were assigned ID values based on historical creel maps or nearby grid ID values. Version 2 of the IFR 10-minute grids was created in 2006 and provides coverage forall five Great Lakes, but only partial coverage in the connecting channels, with no coverage in SCDRS. In contrast to v1, 10-minute grids in this dataset are true 10-minute grids with rectangular sides that strictly follow 10-minute latitude and longitude lines (along with some cases where two true 10-minute grids were combined into one grid cell with one ID value). Due to the differences in grid boundaries, there are some different ID values across v1 and v2. The GLGIS 5-minute grid GIS dataset was created in 2006 at IFR. This layer contains rectangular 5-minute grids that are true 5-minute grids, with each side of every grid representing 5-minutes of latitude or longitude. 5-minute grids were used for SCDRS in v3.2 to align with historical data reporting standards in the region, and because there are no 10-minute grids that fully cover SCDRS. 5-minute grids created by the GLGIS only exist for SCDRS, Lake Erie, and Lake Huron, and the reason for this is unknown. SCDRS grids on the Canadian side of the basin are included in v3.2 for Fisheries Division data reporting needs that may include Canadian areas of SCDRS, but these grids in Canadian waters may not represent the standard that is actively used by Canadian agencies. In order to create the v3.2 composite, grid cells from the various GIS data sources were merged together for water bodies as specified above. In v3.2 the grids are almost exactly as they appear in the source data (with minor edits such as edge matching) except where 10-minute grids 602 and 603 in Lake Erie from Version 2 were replaced with GLGIS 5-minute grids. These grids cover the transition between the Detroit River and Lake Erie, where 10-minute grids are too large for some fisheries data reporting purposes. Therefore in v3.2, the two 10-minute grids were replaced with four 5-minute grids from the GLGIS 5-minute grid dataset. ID values were kept from the 5-minute grids for the two northern cells but the two southern grids cells retain ID values from the GLGIS v2 10-minute grids (602 and 603). This was done to allow continuity with historical data that has been recorded for 10-minute grids 602 and 603, but users need to be aware that these ID values in v3.2 are now associated with 5-minute grids instead of 10-minute grids. Version 3.2 was subsequently slightly altered to create Version 3.3, which replaced the shoreline in Northern Lake Huron and slightly altered the shoreline near the Soo Locks in the St. Mary's River to match zones, closures, etc. described in the Consent Decree that were depicted with a more detailed shoreline than the v3.2 shoreline. This was done so that those zones, closures, etc. could be depicted along with the Michigan Great Lakes Grids and have alligning shoerline depictions (see Figures 13, 12 & 16 for examples of the more detailed shoreline). GIS layer was last updated 10/01/2019. Metadata last updated 10/02/2019. REFERENCE: 1) Technical Fisheries Review Committee. 1989. Status of the fishery resource – 1988. A report by the Technical Fisheries Review Committee on the assessment of lake trout and lake whitefish in treaty-ceded waters of the upper Great Lakes: State of Michigan, Technical Fisheries Review Committee.数十年来，以经纬度分钟为划分依据的网格系统一直作为五大湖地区渔业数据报告的行业标准被广泛使用。密歇根州自然资源部（Michigan Department of Natural Resources, MDNR）渔业分局于2019年创建了此地理信息系统（Geographic Information System, GIS）图层，用以呈现该局针对密歇根州管辖水域以及圣克莱尔-底特律河水系（St. Clair Detroit River System, SCDRS）加拿大水域的渔业应用所采用的MDNR密歇根五大湖网格（v3.2）标准，数据截止至2019年6月。该GIS图层通过整合多套现有网格标准的网格边界与ID值构建而成。 本图层为复合网格，整合了五大湖不同区域所采用的以下GIS数据标准的网格边界与ID值： 1）休伦湖、密歇根湖、苏必利尔湖以及圣玛丽河的10分钟网格数据，源自渔业研究所（Institute for Fisheries Research, IFR）10分钟网格的v1版本（v1）。 2）伊利湖的10分钟网格数据，源自五大湖GIS（Great Lakes GIS, GLGIS）项目所构建的IFR 10分钟网格v2版本； 3）SCDRS的5分钟网格数据，源自GLGIS项目开发的5分钟网格。 IFR 10分钟网格v1版本创建于1998年，仅覆盖休伦湖、密歇根湖、苏必利尔湖以及圣玛丽河区域。该GIS数据集曾作为2000年和解协议的网格标准被使用。v1版本的网格边界与ID值，源自1989年《渔业资源现状报告》（技术审查委员会，1989）中的纸质地图，因将纸质地图转换为数字GIS格式，可能存在极细微的网格边界差异。在v1版本中，10分钟网格并非始终为各边对应10分经纬度的矩形边界，在近岸区域尤为明显。为构建v3.2复合图层，v1 GIS数据集中部分缺失ID值的要素，通过历史渔获调查地图或邻近网格ID值进行了ID赋值。 IFR 10分钟网格v2版本创建于2006年，覆盖全部五大湖水域，但仅部分覆盖连接水道，未覆盖SCDRS区域。与v1版本不同，该数据集的10分钟网格为严格遵循10分经纬度线的标准矩形网格（部分场景下，两个标准10分钟网格会合并为一个带有单一ID值的网格单元）。由于网格边界存在差异，v1与v2版本存在部分ID值不一致的情况。 GLGIS 5分钟网格GIS数据集于2006年由IFR构建。该图层包含标准的5分钟矩形网格，每个网格的各边均对应5分纬度或经度。v3.2版本中为SCDRS区域采用5分钟网格，一是为契合该区域历史数据报告标准，二是目前尚无完整覆盖SCDRS的10分钟网格。GLGIS构建的5分钟网格仅覆盖SCDRS、伊利湖与休伦湖区域，其具体原因尚不明确。 v3.2版本纳入了SCDRS流域加拿大一侧的网格，以满足渔业分局可能涉及SCDRS加拿大区域的数据报告需求，但加拿大水域的这些网格未必符合加拿大相关机构当前实际使用的标准。为构建v3.2复合图层，我们按照前述水域范围，将不同GIS数据源的网格单元进行了合并。v3.2版本的网格与源数据基本一致（仅进行了边缘匹配等小幅编辑），仅伊利湖v2版本的10分钟网格602与603被替换为GLGIS的5分钟网格。该区域为底特律河与伊利湖的过渡地带，10分钟网格尺寸过大，无法满足部分渔业数据报告的需求。因此，v3.2版本中将这两个10分钟网格替换为GLGIS 5分钟网格数据集中的4个5分钟网格。北部的两个网格单元沿用了5分钟网格的ID值，而南部的两个网格单元则保留了GLGIS v2版本10分钟网格的ID值（602与603）。此举旨在与此前针对10分钟网格602与603记录的历史数据保持衔接，但用户需注意，v3.2版本中的这些ID值现已对应5分钟网格，而非原有的10分钟网格。 后续对v3.2版本进行小幅修改，生成了v3.3版本：该版本替换了北休伦湖的岸线数据，并小幅调整了圣玛丽河苏圣玛丽船闸附近的岸线，以匹配和解协议中描述的、相较于v3.2岸线更为精细的区域、禁捕区等内容。此举可使上述区域、禁捕区等内容与密歇根五大湖网格一同展示，并保持岸线描绘的一致性（详见图13、12与16，该类示例展示了更为精细的岸线）。 本GIS图层最后更新于2019年10月1日，元数据最后更新于2019年10月2日。 参考文献： 1）渔业技术审查委员会. 1989. 渔业资源现状——1988年. 渔业技术审查委员会关于上五大湖条约割让水域（密歇根州管辖）内湖鳟与湖白鲑评估的报告. 渔业技术审查委员会。